Clippersfan86

I have a 91 305 TPI 5 speed. I've heard the computer is finicky about exhaust changes on the speed density models like mine (90 and up I believe). I'm really desiring open headers but wondering about the possible consequences. Will it affect my gas mileage or power either in a good or bad way? Will I get a check engine light? I'm not talking about stock manifold... but legit 500+ dollar, aftermarket headers.

I live in California so it's obviously very much illegal but I ran open downpipe on my STI and just stayed out of throttle when cops were around and they didn't mess with me. I know nowadays most look down upon this and consider it ***** or cheap but know that I'm not doing this for the sound. I'm trying to get the most efficient power possible which I've heard is either no exhaust or straight pipes.

TTOP350

iTrader: (8)

Yikes....

gmstrong

Lose of gas mileage,a gutless turd with no low end torque at all.

DeathStarr89

iTrader: (1)

OP, have you ever driven a 3rd gen with open headers?



it's fun for about 5 minutes... then you start having thoughts about exhaust getting back up into the car and knocking you out, fires, HUGE tickets and fines, headaches, etc..


I drove around town once with open longtubes in my '82 T/A, never again.

2007xl50

Yeah not a good idea man. A turbo car's exhasut is never as loud as an NA car's. I stared up my TPI 305 with just the stock Y-pipe when the cat went bad and not good sounding at all and very loud. Right now I have a 24" summit glass pack in place of the cat with a about a 1" spout and it does not sound too bad, but does get loud when you get on it. last year I had a 72 Nova with a mild 307 in it. It had Headman long tubes on it and when i did the muffler swap I drove it around for a few with just the header and about 5' of pipe coming off them. I did not like the sound one bit and the car lost some low end as well. I was very happy to install the new Flowmaster 40's lol!

Open headers are cool on a built engine and on the track or off road.

Clippersfan86

Really? My WRX was LOUD AS FU** when I ran open 3 inch DP. The turbo spool alone was louder than an 18 wheeler's. I just don't want to pay 500+ for a good exhaust. I want to be able to afford headers+full exhaust for around 600-700 tops. I'm debating custom headers and exhaust but I know they usually use crush bent rather than mandrel.

I'm not new to cars but I am new to V8. My previous cars were 06 WRX, 01 S2000, 04 Neon SRT4 and a turbo Civic. With the turbo cars a full turboback exhaust and tune easily gets you 70 hp/tq at the wheels (very lean). I'm not used to NA V8.

Like everybody else I want the most bang for the buck. My 305 is the 5 speed so it has good pickup but I'm used to 350+ whp cars and want more.

If you guys think open headers are this bad how about custom headers+exhaust vs aftermarket? Any cheap/best gains set ups that you guys know of? I looked into hooker headers but I read that they don't work with my 2 cat system (91-92 speed density 305's).

2007xl50

Well your WRX might have been loud, but I have be around alot of built turbo cars and did not have much of an exhaust and they are not a loud as a V8 with no exhaust. Sadly if you are use to thoes pocket rockets you my friend you have the wrong car right now. I love F-bodys, but let's face it in stock form they are not all tha fast. Yeah a good exhaust on an F-body is always going to help. Do you want to keep the cats or ditch them?

Base91

iTrader: (1)

You won't get far in CA with open headers on a v8. It's loud just at idle!!! But, let us know just how far you do get. I'd say as far as the first cop car.

Clippersfan86

I just got my smog/registration about 10 months ago.. so I'm good for a while. I'm thinking run catless/straight pipes... then just swap on my stock exhaust when smog time comes (or find an illegal smog pass). On my turbo cars... ditching cats didn't throw a CEL.... Will the 305? I just talked to a local exhaust shop and the guy was so full of ****. He said if I keep cats I'll gain pretty much ZERO with headers+exhaust. I know with cats I won't gain much but that's unbelievable.

I understand my 91 isn't going to be as fast as other cars. My goals are realistic. 250 whp, reliable daily driver. Not looking for anything much. High 13's or low 14's would work for me. I saw my baby on the lot and fell in love with it. I have never in my life seen another Banshee 91-92 305 TPI 5 speed. So I know I have something very rare and it's been so good to me for almost a year. Literally zero problems besides a little TLC last owner didn't do.

Yesterday I got timing done, new battery, new alternator, new vacuum hoses and some other minor things. I already notice it's running significantly better and I've gained a lot of top end.

Clippersfan86

. I was living in Nevada BTW when I ran the WRX open downpipe (had a pretty big turbo too).

GreggymacZ28

Open headers on a 305 wont pick up anything, you will lose your low end torque. With just shorties and a y-pipe you should have an optimum exhaust for your 305. I'd say go that route and then if you ever start modifying your 305 then maybe you can step up.

Also, no stock 305 will run high 13's in the 1/4 mile. There are guys who ran faster than that on here, but they had some extensive mods to their car. My 305 with headers and y-pipe and ac delete ran 15.90's.

Base91

iTrader: (1)

Here in the peoples republic you're not allowed to make that much noise. It frightens the cyclists and wrinkles their spandex.

TTOP350

iTrader: (8)

It may add a stain or 2 to the spandex also... lol

Clippersfan86

I'm sure you know significantly more about F Bodies than me... but remember I have a 91 5 speed. Bigger head and cam so these power goals should be easier to achieve. I didn't mean 13's stock man . I meant eventually WITH mods I'd love to be high 13's. Which gives me a quick but not fast car. Peppy daily driver.

Currently I have just the stock manifold+midpipe. My muffler rusted bad so I removed the axel back (so no muffler)... just in case anybody is wondering what I currently am stuck with. If I do headers+y pipe... what brands/set ups do you recommend? Ideally I'd want the easiest/most efficient job. I'd love to run catless but not sure if the 305 will throw a check engine light?

VincentZ28

iTrader: (2)

Young dude, you are tripping. You can not run open headers on a V8 car period. And no smog stuff either? Big tickets and big *** fines up to $5000 for tampering with the emissions equipment.

Look up Dyno Don and get his headers. They are the best bang out there and you can run dual cats. Then get a 3in cat back exhaust system from Magnaflow. It will be a cool mellow deep sound and you car will run in the high to mid 13's if you can drive @ 101mph in the quarter mile. I've seem it done before. The headers are not cheap but they will not rust and will last the life time of the car.

TTOP350

iTrader: (8)

Dyno Dons headers and Y pipe. along with a cat back of your choice. For the power your looking at this will be more than enuff. Plus you can keep your cats and all your emissions stuff to keep it a true daily driver out there in ****-ville.. lol
Do some looking and you will find great info.

Clippersfan86

I already have my story ready for a cop . "My muffler rusted out and I'm a broke college student so saving for an exhaust now". Which is actually the truth! . Damn I didn't realize the fine can be 5000 bucks though .

I'll look into Dyno Don right now. I'm starting to wonder if I should just start with heads/cam at this point. The local shop said if I bring him parts he will do the job for 600 or 700 bucks. With the full headers+exhaust I'm not looking at much less and I'm sure the gains of heads/cam would be SIGNIFICANTLY more.

Problem is I'm sure I'd have to buy a custom chip and all kinds of crap. I always thought 80's and 90's small blocks were easy to mod up but man... these 3rd gens seem to cost a ton to mod.

Base91

iTrader: (1)

There is nothing cheap in CA.

Clippersfan86

I need to move back to Reno haha.... They didn't give a damn what you did to cars.

DeltaElite121

It's not expensive in comparison to other cars. You have a 305 though, and those require some serious work if you want to keep up with "everyone else".

VincentZ28

iTrader: (2)

You don't need heads and cam yet. Nor a custom chip but it would help some. You will also need a Fuel Pressure Regulator to help fine tune.

tajoe

iTrader: (1)

Aye Clipperman, nothing like the sound of open hedders on a hot rod V8. I once (many yrs ago), uncorked my Doug Thorleys on a military vacation, for a full tank of gas, driving from LRAFB Ark to Mass. It was all hy-way driving, (65 GTO),and wanted to experiment for the sake of fuel mileage. It didn't do much for that, but made me feel like Richard Petty, everytime I got to pass someone. How it would effect your computer or little 305 I can't say, but it sure is fun. (Unless you get caught and have to pay the piper.). Your choice. Good luck.

Base91

iTrader: (1)

I had short pipes and glass packs exiting under the floor of a 454HO in a '67 Firebird. I did 400 miles on the freeway with them. Never again. OK for cruising around town at low revs with an occasional blast. Especially in a tunnel. But hours on end? No way.

Clippersfan86

Yea my WRX was ear bleeding. Anybody here have a 91-92 that has a recommendation on the best headers/exhaust combo? I don't care about loudness but purely power gains.

WickedCrazy

What the flying F is a Banshee? Are you just referring to a aero kitt'd firebird? And since 305's were the only ones to get 5-speeds im sorry to say your car is not rare at all. Infact its common as hell.

Base91

iTrader: (1)

The Banshee is what the original Pontiac concept car was called that the '91 '92 body style is based on. It can probably be Googled.

Clippersfan86

Banshee is the body style nickname of the 91/92 but as other poster said it was the code name of the concept model. You really need to do your homework if you think GTA model 91 5 speeds are common for the trans am. Try production number of 2,300 total and less than 300 5 speed from what I hear. That's extremely rare. That's not even getting into specifics like color, WS6 suspension package I have etc. Chances of me ever in my life seeing another 91 305 5 speed drive by are astronomically low. I've seen one other 91 but it's the V6 RS. Also you failed in researching because almost all 91 and 92 305's were automatic.

Point is... If you're gonna be a douche at least do the research.

http://www.autotrader.com/cars-for-s...Radius=0&Log=0

Searched for 91 5 speed Trans Am on auto trader with no distance restriction and guess what I got? ONE.

Cars.com had zero matches to that criteria. Those are the two biggest used cars searches on the web. Yup... very common, dime a dozen.

Clippersfan86

Just found another thread on this board that said only 154.. 5 speeds were made for 91 Trans Am. So yup... Pretty damn rare. Another example of 5 speed rarity can be seen in the 91Camaro. 100k total Camaro's were made and only 15k had a 5 speed. That includes all trims and all 3 engines.

Anyways this is off topic. Only reason I specified my car was because 90 percent of the threads here are for 350's or pre 91's. Which is no good to me because I have 2 cats, speed density and bigger stock head and cam than both automatics and previous years.

BADASS91B4C

dont know if this helps but i live in reno like you said you used to and i ran open headers on my 350 for like a year straight (car is being rebuilt and will probably have open headers when back on the road) and never got pulled over by the cops but when my car was e.f.i. the open headers made the knock sensor go off and retarded the timing ....... so open headers will hurt ur efi performance if its anything like my experience. but i have taking my newly carbed motor out with open headers and it was loud and fun as hell. .......... not sure if any of this makes sense i just got back from my 10 reunion and i am kinda wasted ...... hope my post helped

tajoe

iTrader: (1)

Point is... If you're gonna be a douche at least do the research.

Yup... very common, dime a dozen.[/quote]
LMFAO

Clippersfan86

I appreciate it and yes it helped. You guys basically convinced me that open headers is stupid on these cars lol. I've already decided im going to get intake, headers and exhaust same day and install. I just need to figure out a good trio of parts now so I can have max gains possible. You guys have been very helpful on this forum.

Andrew James

iTrader: (3)

I have run open headers on a few vehicles. I have never looked back or regretted it either. I did a ten hour trip on a open header 302 V8 Bronco and I didn't get tired of that sound once!

Clippersfan86

Haha... on my WRX I told you guys I ran open DP. I also never got tired of it despite my car shaking like crazy and people asking me wtf is wrong with my car. The only louder car I've run into was an older 2nd gen Camaro fully built with crate motor. Point is... like you, the noise doesn't bug me at all. The biggest problem though is remember I'm in California... where cops are car ****'s. They want any excuse to pull you over or crush your car.