So I'm currently sporting a flowmaster 80 with no cats, mid length headers, and a mild cam (.480/.488 low duration). My car sounds like a diesel truck unless I'm really getting on it, not like a muscle car. I want something deep and rumbly, not raspy like the flowmaster. I would really like a muffler that can easily be cut and welded in to the current spot of the 80. Performance wise, well if I lose a couple of HP to get a decent sound I really don't care, I doubt the butt dyno will feel it. I've looked at vids but those little microphones don't really pickup the sound. I also don't hear any lope, I know the cam is mild, but any chance I could get some lopey sound out there

is it a traditional 1 in 2 out muffler?

actually the flowmaster american thunder 3" sytem has a nice deep throaty sound, same 80 series muffler. your specs say you have a 350, so it should sound really good with the flow in there not like a diesel. now if you had a 305 i could understand cuz a 305 sounds like crap without the converter, like a tracter, no matter what muffler you use. if you would like the deeper sound throw in a flowmaster super 40, but youd only have one exhaust exit. but it would sound deep and throaty, personally dont go with the super 44 they say its the most powerfull sounding flow yet, but my buddy has a couple on his elcamino, and its very raspy and poppy sounding, not deep and rumbly at all except for idleing. actually i find it a very annoying sound.

i agree my american thunder cat back sounds awesome. 383 with a .490/.490 lift cam 110 degrees lobe seperation. its also a heddman shorty header and no cat car.

and i dont think the flowmaster kit sounds too bad ona 305 with no cat

sick *** formy ziggy

y thank you

If low and throaty is what you want, then this is what you need.







^^^ Trying it out after it was installed. The GMMG makes my stock cammed car sound like it has a cam. This is stock manifolds, high flow cat, and the GMMG exhaust. It sets off waaaaay more car alarms than my Flowmaster American Thunder ever did.


http://www.ls1sounds.com/GMMG/GMMG_before-after.mpeg (stock vs GMMG....Part of what sold me on the system in the first place)

I've used the Hooker Aerochamber mufflers before and those give you a nice deep sound.

Yeah I would also say go with the hooker aerochamber, its a great sounding muffler.

QUESTION Reid: RE: the GMMG Exhaust Tips - Are they straight cut or are they angle cut? The photo with the GMMG installed appearsto be a straight cut but the photo with the exhaust system by itself appears to have an angle cut. Which one did you get with your GMMG exhaust when you ordered it?
Do you get the drone when you are on the highway? It appears that this exhaust will be very loud when installed with headers - would you recommend getting resonator exhaust tips in this setup? I REALLY like the sound of this exhaust. Thanks for advising

In all honesty, even my weak little 305 (though honestly if this is weak, I'd love to ride in a "fast" thirdgen!) sounds nice and rumbly with my American Thunder catback, at least in my opinion. Not too raspy, not obnoxiously loud either, just a nice, mean rumble at idle. I'm happy with it, though largely because it was on when I got the car.

I love those GMMG's. Everyone is real picky about their exhaust sound, I'm no different. Even when releasing the throttle it make a sweet sound. I'd seen a fourth gen with this setup but never a 3rd gen thanks for uploading this I think I'm sold. After looking through all the interwebz for exhaust clips this is definitely what I'm going with.

The tailpipe choices are 2.75" slash cut circular pipes (think Flowmaster style) or the optional oval pipes. I went with the oval pipes.

Here is a picture of the GMMG with the slash cut tailpipes.



Your choice of tailpipe depends on if you want the sleeper look or a bit more bold looking. Either way, when you walk up behind the car, you'll see the sideways muffler area. I like the ovals myself.

I wouldn't recommend resonator tips. But I would recommend running with a catalytic converter. My car with cat and the GMMG is slightly louder than the American Thunder without cat was. And since the GMMG really doesn't reduce the sound as much as tune the sound, the cat will effectively become your muffler. The sound clips of cars I've heard without cats tend to sound choppier (which I don't like as much as the smoother catted cars)

With headers, it should be even more fun. Highway drone is ZERO.

I'm not sure if GMMG still sells these exhausts anymore. Vengeance racing has been selling them as of late, but they appear to be backordered too. I'd give either company a phone call and see what's up.

A bit of background on my car. In 1990, it got a Flowmaster American Thunder and no cat put in. It sounded great. Low RPM rumble. Loud at high RPM. A bit of drone around 2200 RPM, but not nearly as bad as the drone I've heard on trucks with Flowmasters.

However, after 15 years of the system being on there I got a bit bored with it. I'd go to a car show and every 60's and 70's muscle car would have Flowmasters. Of the 3rd gens at the shows, 70% of them would have a Flowmaster, 20% would have a Hooker, the other 10% would be stock or some other kind of catback. I'd pull into a car show and nobody would notice me because I sounded like every other car there.....once the GMMG went in, people started noticing me and coming over to see what was in there. The system looks cool enough that I'd get some questions about what was it and what brand was it?

The Hooker catbacks are rather interesting. A friend of mine had an LT1 with headers, no cat, and the Hooker catback. At idle it sounded quieter than my GTA with the Flowmaster did. But once he got on the gas pedal it roared. So the Hookers are great if you want to not bother neighbours at low speeds, daily driver, but still loud when you want. The Flowmasters are loud all the time.

But I got hooked on the GMMG sound. I always liked both the low RPM muscle car sound and high RPM Lamborghini sound. The Hardcastle & McCormick Coyote sound. The GMMG is as close to both as you can get. So it has more sounds than the Flowmaster does. Lopey at idle, muscle car at low speeds, and then a bit more exotic sounding at high RPM. I never had any issue with the Flowmaster being aluminum because my car was a summertime only car. But the GMMG being stainless steel all the way through is a nice touch.

I actually had a cop follow me from work one night for about 5 blocks about a month ago. I'd switch from a main road to a side street, he'd follow me. I thought he might be wanting to give me a ticket for no front plate. But when I got to a stop light, he pulled up beside me and gave me the "roll your window down motion." At that point he asked me what kind of exhaust I had and was it available for trucks?