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My opinion is the Flowmaster design uses backpressure to kill sound waves. Their convoluted flow path and reduced diameter passages kill flow for mid to high rpm power. Its quite obvious they are the flow restriction in an exhaust pipe, hence why I started calling them Flowdisaster.
I personally think they can sound pretty good. However, I have been using Magnaflow and liking them although I now think Borla is the best since its 304ss and about 40% lighter than a Magnaflow.
I had a '00 Formula with the very pipes Don posted and a 3" Magnaflow with ~24" case single/single outlet, the sound was quite good, especially at 4,000+ rpm, it started to sound like a mix between a v8 and sportbike. Yes, I prefer the deep "tuned" sound over the gurgly hollow sound of Flowmaster. The performance gain on that was very noticeable.
I just ordered these same Walker pipes today for my '82 and I have another Magnaflow 6" round single/single to cap it off, I can't wait to hear it in few weeks
Last edited by E.Roy; 07-23-2015 at 10:26 PM.
Reason: more details
Are the Walker pipes mandrel bent. I haven't seen mandrel bent from Walker before.
Yes, they were mandrel bent 5 years ago when I bought them for my Formula, and I just received them today for my '82, still mandrel bent, quite cleanly as well. They come with Dynomax stickers on them.
Last edited by E.Roy; 07-27-2015 at 07:46 PM.
Reason: still mandrel bent
i got the same one for gta and i LOVE it everytime i drive it someone compliments on it i chose to keep tips on dont like sending hot exhaust into plastic bumper
I was reading some flow test results this weekend for a bunch of different mufflers and according to the chart, the Magnaflow muffler being tested appeared to flow more straight pipe? Is that for real? Cause that's hard to believe. Has anyone else heard of that?
I was reading some flow test results this weekend for a bunch of different mufflers and according to the chart, the Magnaflow muffler being tested appeared to flow more straight pipe? Is that for real? Cause that's hard to believe. Has anyone else heard of that?
Yeah, it's likely true because the inside diameter of the muffler is larger by double the wall thickness of the exhaust tubing.
3.0" ID muffler= 7.069 sq in area
2.875" ID exh tube= 6.491 sq in area (16ga or .065" wall)
That is a 9% increase in cross sectional area between a muffler and tube,
so it makes sense it should outflow tubing, it is larger.
Yes it did. I found the test with a google search for muffler flow comparisons. There were several flow test comparos that came up in the search. I can't remember who did the one in question. In this test, the Magnaflow, as I remember, outflowed every other muffler, as well as straight pipe. It didn't just outflow them at any certain range either. It made more HP and TQ throughout the engine's RPM range. I guess I just don't see it. It's just a glasspack in a nicer package. I don't see how it would flow more than straight pipe. I do get that maybe it's larger ID. That makes sense.
I have looked through all brands of mufflers doing extensive research before I purchase materials to build my new exhaust. I currently run SLP 1 3/4" primary headers(great product BTW, except that plug changes are a major operation), SLP's single cat y-pipe which is sadly only 2.25" and certainly chokes my motor at the upper range, and a 3" cat back that was orgiinally an Edelbrock product but the cheapy muffler that came with it came apart after several thousand miles and was replaced with a Flowmaster 80. I know I'm giving up power at the top end, and yeah I like the sound but I will get the same and even better sound from dual Powersticks.
My current plan is to build my own dual system, re-using the SLP headers as their still in great shape after 35Kmi. I plan on using Dyno Don's Y-pipe but converting it into dual outlets, just to get me past the engine bay, then into a stamped x-pipe located where the cat was originally, then dual pipes following the factory exhaust routing, through dual Powersticks and reusing the Edelbrock 2.5" tail pipes as their still in good shape.
The one thing I'm still not sure of is whether I want to go dual 3" from the Y-pipe through the mufflers. I have thought of going 2.5" from the headers and transitioning to 3" so that the 2.5" is of even length from the headers. Then staying 3" through the mufflers. I read one article following a drag race team as they test various exhaust configurations comparing ETs and trap speed. They found benefit from having 2.5" pipes off the headers for several inches(sort of like a venturi, accelerating velocity for better scavenging) with cone transitions to 3" through the mufflers, and cones back to 2.5" out of the mufflers. In fact they saw no difference between 2.5 or 3" tail pipes from the 3" mufflers. By that point the gases have cooled to point where volume is reduced so that the smaller pipe makes no difference. The key they found was using cones for the transitions to prevent turbulence. It's the same principle as gasket matching.
Dual 3" will require alot more fab work and re-engineering the track bar brace and the track bar mounting points in order to keep it level to the axle. I don't know if it's worth all that. My realistic power goal is probably 500-540hp. Is there really enough benefit with 3" duals, over 2.5" duals, to make it worth all the work? That's the question. Either way, I'll use the 3" Powersticks with cone transitions just for less restriction.
...My current plan is to build my own dual system, re-using the SLP headers as their still in great shape after 35Kmi. I plan on using Dyno Don's Y-pipe but converting it into dual outlets, just to get me past the engine bay, then into a stamped x-pipe located where the cat was originally, then dual pipes following the factory exhaust routing, through dual Powersticks and reusing the Edelbrock 2.5" tail pipes as their still in good shape.
The one thing I'm still not sure of is whether I want to go dual 3" from the Y-pipe through the mufflers. I have thought of going 2.5" from the headers and transitioning to 3" so that the 2.5" is of even length from the headers. Then staying 3" through the mufflers. I read one article following a drag race team as they test various exhaust configurations comparing ETs and trap speed. They found benefit from having 2.5" pipes off the headers for several inches(sort of like a venturi, accelerating velocity for better scavenging) with cone transitions to 3" through the mufflers, and cones back to 2.5" out of the mufflers. In fact they saw no difference between 2.5 or 3" tail pipes from the 3" mufflers. By that point the gases have cooled to point where volume is reduced so that the smaller pipe makes no difference. The key they found was using cones for the transitions to prevent turbulence. It's the same principle as gasket matching.
Dual 3" will require alot more fab work and re-engineering the track bar brace and the track bar mounting points in order to keep it level to the axle. I don't know if it's worth all that. My realistic power goal is probably 500-540hp. Is there really enough benefit with 3" duals, over 2.5" duals, to make it worth all the work? That's the question. Either way, I'll use the 3" Powersticks with cone transitions just for less restriction.
Sounds like dual 2.5" will be better, at least off the headers, and into a high flowing X-pipe, probably not a stamped one, some appear optimized for fitment not power.
On my 400hp build, because of my oilpan, I had to build my own Y-pipe. It is dual 2.5" copying Dyno Don's. I am building a true merge collector that will transition to single 3" and use the Dynomax/Walker pipes in post #1.
That looks like very clean work. My current plan is to use one of Dyno Don's y-pipes and modify it as needed. Perhaps it would be easier to just fabricate my own to fit. I agree that at least on my car there is not room for 3" from the headers. Besides my SLP 1 3/4 primary shorties are 2.5" at the flange. The SLP single cat y pipe then chokes down to 2.25" onto the y-pipe where it becomes 3". I guess for the dual cat applications they offered a dual 2.5" down pipe that led from the headers to the cats. That would be perfect for my project but alas, like so many others, SLP has abandoned the thirdgen. I've thought about calling them to see if any of those parts are still available on request. They are not listed on their website.
I am thinking that there will minimal power loss at the 500-550 range from short(25-30") 2.5" headpipes off the headers. In fact this will most likely encourage midrange scavenging as the pressure drops going into dual 3". I have also thought of not using dual 3" and just going dual mandrel bent 2.5" throughout. At 550hp, it shouldn't be that restrictive. I do want to try my idea though, just to say I did it, we'll see what I end up deciding. Dual 2.5 will be alot less trouble to engineer.
I was thinking that the stamped x-pipes were meant to flow better. The one I'm looking at is offered by Classic Chambered. I'll have to do some more research on that before I decide. Thanks for your input.
Thanks for liking my work. This was my 1st scratch built y-pipe and it was hard. I had to buy tight radius (2.5" rad) elbows since the hooker header outlets are 3" and i had to reduce them to 2.5". Its good that your SLP's are 2.5" at the flange
This has to be close to the hardest rwd chassis to build exhaust for. Its a bit discouraging actually when you set out to design an optimal exhaust and it all has to be compromised around this awkward chassis design. I would think twice about building your own y-pipe. If you have the money, its so much easier to buy one that fits, but you can build one, I did, well, it is almost done.
I know Don has the dual cat y pipe. I did some research, actually a keyword search for threads that mention his headers and y pipe. I saw a set of his headers with a dual cat setup on one thread.
I wish I had Don's headers. They are art pieces and It looks like they would make my plug change a whole lot easier. Currently, it takes about 4 hours and a variety of tools to do the job. Fortunately, I don't put alot of miles on my car. 37K in the 15 years since I built her. That helps make plugs last longer. That and the AC Delco platinums that I run.
I know these chassis are hard to fit exhaust to. I've seen some decent systems installed, and many not so hot systems. I know that mine will take some hours, days and weeks to do. But it's all worth it.
Another option for the I-pipe is AP Exhaust X5500. Its fits with just a little massaging, the hanger bracket on the bend by the muffler needed to be moved on mine, and the straight part going into the muffler was a little long and pushed the muffler to far to the drivers side. I found it on Summit and then ended up buying it on Amazon. I had the "cat" end stretched to 3" ID to slip fit walker 42760 3" 45 deg elbow. That mates to an 18" long 3" pipe to replace the cat(my car never had one when i bought it) and that fits into the elbow from dyno don's y-pipe.
I put this into the Magnaflow and used the dynomax tailpipes, its agreat sounding system and would recommend it to anyone looking.
I'm going to go with the hedman y pipe just to save myself the headache of building one and then 3" from there back. The section the catalytic converter occupies is the only part I'll have to do from scratch it looks like.. Perfect.
From AP exhaust, even though it's only 2.5" and I did keep the stock convertor. I got their complete kit: X6501 midpipe, x3000 and x3001 tail pipes, xs2265 stainless steel muffler, 8165 and 8024 hangers, plus lap joint clamps from Summit for $250. I too wanted a stainless system, however I couldn't afford the $530 for the Magnaflow. I tried to get the Dynomax ss system, but it was going to be 3 weeks before they made it, that was after talking to their manufacturer Technico about production. To try to keep exhaust temps down and preserve the pipes from rust, I took them to a coater in Virginia Beach and had all of it ceramic coated for $100. I did not have them paint it, I used VHT universal aluminum as my color choice $6.99. It may not be stainless but it's as close as it's going to get for a good price I think.
when I installed this I shifted the I-pipe back to use the existing bracket on it into the factory frame mounting point. This provided better clearance for the I-pipe over the panhard brace (you can see how tight it can be otherwise in the photo above). This required me to re-install the frame bracket for the left tail pipe approximately 1-1/2" rearward, which only required a drill and self tap. This squared up the muffler under the car.
With my Magnaflow muffler I still had plenty of clearance between the muffler and heat shield. Other mufflers may be wider and not provide enough heat shield-muffler clearance.
when I installed this I shifted the I-pipe back to use the existing bracket on it into the factory frame mounting point. This provided better clearance for the I-pipe over the panhard brace (you can see how tight it can be otherwise in the photo above). This required me to re-install the frame bracket for the left tail pipe approximately 1-1/2" rearward, which only required a drill and self tap. This squared up the muffler under the car.
With my Magnaflow muffler I still had plenty of clearance between the muffler and heat shield. Other mufflers may be wider and not provide enough heat shield-muffler clearance.
I agree its tight over the pan-hard brace, that picture is a bad angle, and there is some clearance, but its tight.
The good news is i intentionally drove down the bumpy road and i didnt get any rattles or clunks, so at this point i think im in good shape.
Just did a 3" catback on my bird. I make 500-550hp with a supercharged 5.3 LS. I had a 4" exhaust but didn't like the on the throttle noise and needed the PHB relocation etc.
Almost went with the peices in this thread but glad I didn't I originally purchased a summit 4th gen catback 3" and it fit like poo. Basically resting on the PHB support like the pics above show, then clearance to the axle is not great. Realizing this I had summit swap the 4th gen catback to a 3rd gen kit same summit racing brand. Recieved the new kit and took some comparison pics, the over axle pipe is not the same and makes all the difference with the PHB support. Not i have alittle clearance to the PHB support and the over axle clearance is much better. However getting the 82-92 over axle pipe in was a PITA much harder than the 4 gen as its all one large peice.
FWIW hp rating of a 3" pipe or catback on our cars is about 450hp before it becomes a restriction. 4" is good for about 600hp. If your putting out 500hp your prob not loosing that much power with a 3" kit as the velocity is still very high. However going to a 4" you might loose a good bit of low end until the higher ranges due to loss of velocity. And unless your spend all your time in the high RPMs its ok to have a slightly undersized exhaust due to flow under the curve.
I'll post pics of the exhaust differences in a min.
Last edited by customblackbird; 07-29-2016 at 11:42 AM.
I'm trying to design a 3" cat back system with a cutout similar to the Borla design.
I currently have Dyno Don's headers and Y-pipe on a 305 TPI. I currently have no cat and exhaust after y-pipe is existing 2 1/4 inch exhaust back to what I think is a Flowmaster muffler. Exhaust seems very 'airy' and 'clappy' in lower RPM's while accelerating. Did not sound like that before putting on headers and y-pipe.
In case the picture is not clear, here is my idea in word form starting from the y-pipe: 1) y-pipe to 2.5" to 3" adapter; 2) then 53009 Magnaflow universal cat (3" in/3" out); 3) 41428 Walker exhaust 45" elbow; 4) then APH X5500 intermediate pipe; 5) then roughly at the intermediate pipe's rear hanger, cut in an SUM-670137 Summit Racing exhaust cutout; 6) [passenger side exhaust out] then from the cutout attach a SUM-G4752ID exhaust reducer attached to a 41428 Walker exhaust 45" elbow; 7) then the piece of intermediate pipe cut off attached to exhaust cutout (modified for length) and then 11229 Magnaflow performance muffler (3" single in/3" single out); 8) [driver side exhaust out] 41685 Walker exhaust 90 degree elbow.
Not including shipping, clamps and hangers, all of the parts after the y-pipe listed above from Summit
come up to $464.94.
A lot the parts listed in this thread, due to age, are no longer available so I tried to piece together something similar.
Your almost at the cost of a 4" mufflex catback. I no longer run a 3" catback but a 4" mufflex kit from Hawks and I put a vibrant SS muffler on it. With the turbo the exhaust tone is very mild.
You can cheap out on quite a few parts to help bring the costs down. Sounds like a 3" would be overkill for you likely and doing all the stepping up and down is going to hurt you cost wise. Summit makes a catback and you could keep the dual pipes and maybe work in the cutout.
- cheaper Cat
- Summit cutout is same as ebay (Grannelli/jegs etc) they are all offshore just rebranded
- swap the Magnaflow for a Jones performance and cut the price in half.
if your 305 is putting out 300+hp then go with 3” for sure. Your cheapest option would be a summit or jegs 3” catback and there is no piecing together. If you opt for no cat you can get a cutout under where the cat was. For a stockish 305 a 2.5” catback is adequate.
I believe the summit is a rebranded t
hearthrob exhausted. I ran it for a bit and wasn’t terrible. I prefer hidden tailpipes tho so had to get dynomax tailpipes.
customblackbird - using cheaper muffler (Jones Max Flow) and a cheaper universal CAT (WaSaett from Amazon), I got the total build to right at $410 (including clamps and connectors) before taxes and shipping.
I also like the hidden exhaust look. Currently I just have turn downs without tips. I think for this build I might use black tips and have the pipes run down just enough for the tips to be barely viewable.
All I know for sure is this is a much better alternative to getting a Borla catback which I originally wanted. I had Borla on a '96 Z28 and really liked it. Of course, back then, Borla was no where near the $2,000.00 it is now!
customblackbird - using cheaper muffler (Jones Max Flow) and a cheaper universal CAT (WaSaett from Amazon), I got the total build to right at $410 (including clamps and connectors) before taxes and shipping.
I also like the hidden exhaust look. Currently I just have turn downs without tips. I think for this build I might use black tips and have the pipes run down just enough for the tips to be barely viewable.
All I know for sure is this is a much better alternative to getting a Borla catback which I originally wanted. I had Borla on a '96 Z28 and really liked it. Of course, back then, Borla was no where near the $2,000.00 it is now!
ok, is that including the cutout kit with flange and controller? How are you welding the adapter to the over axle pipe?
The cutout is not going to be electronic, so no controller. I am going for a Borla design where I can use different 'adapters' to allow more or less exhaust flow.
For the time being I plan to clamp everything (the cutout is 3" ID while the intermediate pipe is 3" OD). Once in place I will have a shop weld everything together.
Ok, I made some item changes to save money and did a slight redesign at the cutout. See new diagram.
I decided to go with the AP XS1229 Muffler. It is supposed to be same as Magnaflow, Flowmaster, and Jones versions. I also decided to go with a CAT from Amazon. This is the only piece I am little worried about.
Below is total pricing.
$225.17 (Amazon)
- Exhaust tips (2)
- 2.5” ID to 3” ID coupler
- 3” ID to 3” ID couplers (2)
- CAT
- Muffler
- 3” hangers (2)
- 3” clamps (8)
$292.76 (Summit)
- Intermediate pipe
- Cutout
- Reducers (only need one but comes in a pair)
- 45 degree elbows (2)
- 90 degree elbows (2)
$517.93 total (Total does not include 2.5” clamp for Y-pipe to 2.5” ID to 3” ID coupler as I already have one. They are less than $5 on Amazon)
I hope to post pics as I construct.
The summit catback is $375, add your cat and I assume vacuum operated cutout/loud valve and be done with it. Just splice it into the over axle pipe that runs in front of the passenger tailpipe with a small turndown. You’re not going to gain much from opening the cutout if any for power being a 305 and you get the loudness you want. I will tell you having a cutout on a boosted 5.3 with a custom cam can sound wicked but I don’t tend to open much if at all. Gets old quick and attracts attention. I prefer not to be quieter and fast. cats are $30 and boost valve is like $50
customblackbird - I could just go with the APH-X5500 Intermediate Pipe, the Walker Direct-Fit Tailpipes (43243 and 43244), two Walker 2.5" U-Bolt Clamps (35337) to attach tailpipes to muffler, a Walker 3" U-Bolt Clamps (35794) to attach the intermediate pipe to the muffler and grab the Summit Racing Muffler (SUM-638270) for $279.77 including shipping and taxes. This is essentially the same thing as the Summit Racing Cat-Back System except the Summit System has a two piece intermediate pipe and is $127.24 more expensive.
The Summit Racing Cat-Back System (SUM-680022) is $407.01 including shipping and taxes.
Ok, I know old thread. My question is did anyone figure out the solution to adapt a Magnaflow 93441 to the collection of part Dyno Don listed or the APX-5500 intermediate pipe? I see the notion of a 3" slip fit cat instead of the 93441. I would prefer stainless but also am firm on a stock tailpipe appearance so since my car is more a garage queen would rather stick with the appearance as it likely won't see salt anyway.
Perhaps the solution is not to use the Maganflow 93441($297) but the suggested by @hassgrant (much cheaper) WaSaett 3" above ($31)
My potential list:
Dyno Don Y-Pipe off his headers
WLK-43243
WLK-43244
WLK-53061
WLK-54064
or instead of above it sounds like APH-5500 intermediate pipe will work
MPE-12267
hessm70 - I think I actually have Doug's Headers and Y-Pipe instead of Dyno Don's. Either way both should be 2.5". I have decided to not go with a CAT and I think I am going to try and use a 3" mandrel bend aluminized pipe kit from Amazon that right now is $120.00 (listed at $135.99 but right now has a $15 coupon). The kit includes 2 48" straight pipes, 2 45 degree elbows, 2 90 degree elbows, and 2 U's. All pieces have one end that is 3" OD and one end that is 3" ID so they will slip together. Using this kit (still have to measure current setup - car is back at the paint shop right now for some touch ups), the only other things I think I will need for my setup will be a 2.5" ID to 3" OD coupler to connect y-pipe to straight pipe replacing CAT, muffler, cutout, reducer, hangers and clamps. With shipping and taxes, the build comes in at $420.67. If you don't want to put a cutout, you can save about $70 to $75. Even the Summit cat-back kit is right now $401.01 with taxes and shipping and that does not include a CAT or a straight pipe to replace the CAT.
Once I measure under my car and determine if the pipe kit is enough (I have the feeling I am going to need an extra 45 and 90 because not sure if I can make the U's work), I'll take pictures of the progress and build and put up a list of all items and what I did.
Ok, I purchased all of the parts today. Total cost was $413.21. I ended up getting the 2.5" ID to 3" OD coupler from Summit, even though it was more expensive than on Amazon, because it made my purchase enough to get free delivery. You can see purchased items and prices below.
So I finally finished the custom exhaust. I did have to buy four more 3" u-bolt clamps and a 3" ID x 3" ID coupler. However, I did not use two of the hanger clamps. I picked up the coupler and clamps at my local Advance Auto Parts for $29.49. That two hanger clamps I didn't use were $28.95, so almost a wash. I have included some pictures below and PDF describing what I did. I have a video with the exhaust 'open' but I don't know how to share.
Wow, nice write up @hassgrant. I have heard that the AP Exhaust mid-pipe APH-X5500may have some bend restrictions around the axle so I was researching exhaust shops in my area to do a mandrel bended version but if I cannot find that, I will consider using the bits you used for that midpipe.
So I finally finished the custom exhaust. I did have to buy four more 3" u-bolt clamps and a 3" ID x 3" ID coupler. However, I did not use two of the hanger clamps. I picked up the coupler and clamps at my local Advance Auto Parts for $29.49. That two hanger clamps I didn't use were $28.95, so almost a wash. I have included some pictures below and PDF describing what I did. I have a video with the exhaust 'open' but I don't know how to share.
Looks like it worked out for you. Alot of connection points and you would be better off switching out all the Ubolt clamps for accuseal band clamps to clean things up especially from the back pass tip area. U bolt clamps deform the pipe and make taking it apart a PITA plus they rust and look terrible.
For video the best is to create a youtube account, upload the video and copy the share link and post it in your reply.
customblackbird - I agree about the band clamps. I went with the u-bolt clamps for this build due to cost. The back passenger tip is a clamp hanger and I might move the hanger back so it is more out of sight. I'll work on creating a YouTube account and then share the link.
07-23-2015, 10:08 PM
