EDGE

Just did a head and cam change. Running Edelbrock TES headers and have for over 20 years. However I just changed the Y-pipe to a Dyno Don's mandrel one, and into a 3" catback. The car sounds awesome hammering it around town and at idle. Especially on the down shifts. But it's insane on the highway. The drone is unbearable. Never heard anything like it before. It's not a nice sound at all, and bloody deafening at that. I need to do something so I'm open to recommendations or any mods any of you have done to try and control that droan.

BadSS

Dynomax Welded Ultra Flow 17227 if you can find one in stock. It's fairly quiet at cruise and has a relatively quiet but deep rumble to it. However, it gets pretty loud under wide open throttle.

Never tried it, but the MagnaFlow 12267, although it appears to be slightly smaller in width, would probably sound similar to the 17227.

Buddy

Yea, Magnaflow is nice. Quiet cruising but has a good bark on throttle hard.

EDGE

Yeah I'm leaning toward the magnaflow. I do love the pops and cracks of the Flowmaster on the downshifts though. Hopefully the magnaflow does the same.

EDGE

Any thoughts on adding a Dynomax 24250 straight through muffler as a resonator and just leave the Flowmaster?

Firechicken82

You could probably place a resonator where the cat would be and reduce any drone that way. Also quiet it down a little.

BadSS

A single 3" exhaust system with mandrel bends flows enough to support about 325HP without losing any power. The straight through mufflers like the Welded Ultra Flo and the MagnaFlow flow enough to easily support 325HP. I've never seen an 80-series flowed, but a 3-inch, 2-chambered 40-series only flows enough to support about 185HP before robbing power. The 40 series will flow more than the 80-series. As you can see in the picture below, the "exit area" and dual exit pipes takes up over a third of the 80-series muffler volume - so the actual muffler size is something like 6-wide x 10-long x 5-deep. So it’ll start robbing power on an engine making less than 180HP. It’s a terrible performance muffler - your engine deserves better and will thank you.

EDGE

Ordered the Magnaflow 12267. Seems like it will do the trick. That Flowmaster sounds great at idle and light to light but completely intolerable at cruise. Deafening actually. Was toying with the idea of an Aerochamber as well but that Magnaflow, based on the sound clips, seems to have it in all the right spots. @BadSS that FLowmaster chamber looks like a recipe for very turbulent air, especially the turn to the outlets. Spend all that time and money on the front end streamlining the incoming air only to bung it up on the exit side makes no sense to me.

vinny R

I used the Hooker Aero Chamber and love it. It is a 3" mandrel bend system with a DynoMax mandrel bend Y-Pipe. This sounds great when stomping on it, really opens up with a great tone and has that crackle on deceleration and I run exhaust manifolds. I can't tell you how many peeps tell me that there is no way I have a 305 with the sound of my car. It really does sound like a 300+ hp 350. The best part is absolutely no droan at cruise or anywhere in the power. Great muffler for our cars IMHO.

Buddy

Update your opinions when you get it on the car and drive around a bit.

EDGE

So the muffler is installed. Pretty happy with it. It's a muted but more airy sound than the Flowmaster. I find it a little to quiet at idle but I know that'll change when it breaks in. Getting on it is not much quieter than the Flowmaster, however the raspiness isn't there and I was never really a fan of that. The big win is the drone. At 100 kph it's completely gone. Theres enough of a sound there to know it's no 4 cylinder but it's quite pleasant. The downside is I can now hear the Scorpion roller rockers that mimic a sewing machine.

BadSS

Glad you like it - thanks for the review. I didn't have any drone with the Welded Ultra Flo, but was a little worried that the MagnaFlow might (since I've never run one).

If you don't have a wideband O2 sensor to check your air/fuel ratio, check your plugs. If it was tuned for the Flowmaster, more than likely you'll need to add some fuel for the MagnaFlow - especially under WOT.

EDGE

I do have a WB O2 and it seems to be okay

BadSS

That’s not entirely surprising for idle, cruise, and moderate part throttle with the MAF system. However, I would have lost money betting your AFR would have shown lean under WOT - unless it was running a little rich at WOT to begin with.

EDGE

Sorry for the delay in response. Had some time to get a lot of good rides in. The WB on the AEM gauge sits at 14.5 to 14.7 pretty much all the time in the cruise range. When I drop it and get on it up to around 5200 RPM at dam close to WOT and the odd WOT I'm seeing that gauge drop down to 11, so it's adding the fuel and has quite the get up and go. Smells perfect too. I do get screwy readings at cold idle as I am running AIRS so depending on when that's active I'll get some lean readings but normally nothing beyond about 15 other than decell cutoff of course. Happy with this muffler so far. I can feel it in the midrange pull above 3000 RPM