I have heard a lot of great things about the GMMG exhaust and have thought about getting one but I'm not sure if it's worth swapping cat-backs for. I am planning on getting some mid-length AS&M or RK Sport headers as soon as I get back from my deployment and I currently have an SLP Loudmouth with a chambered muffler in place of the resonator. Will the GMMG sound different enough to warrant the swap?

 

It'll sound a little different due to 2 mufflers instead of 1, but is that sound worth $700? There will be no power gains. If you want power gains and sound get duals with those headers.

 

I'd be interested in purchasing your existing setup should you decide to switch. I was thinking of doing the same thing you did with the LM. How does it sound bro? I am very interested in hearing a sound clip if possible. Been curious about this mod for a while now. Thanks

Will

 

You could easily have a true dual exhaust for cheaper than $700. Summit or Jegs sell universal x-pipe packages. It just depends on what mufflers you'd go with.

A custom exhaust shop could offer you even more

 

I think it sounds better than the LM with just the resonator- it is less raspy and a little deeper. Unfortunately I have never heard the GMMG in person so I can't compare, but I would imagine my setup is a little louder. The more I think about true duals with chambered mufflers, the more I like that idea, but who knows.
I won't be able to get a sound clip until I get back from this deployment in a couple of months.

 

I have GMMG with pacesetter LTs and offroad y-pipe with some pypes mini cats welded in i think it sound awesome. Will probably be even nicer once my car is finish being rebuilt and has a 383 in it. Maybe when i get back from my deployment i can put up some sound clips.

 

I have the RK sport headers and the Borla adjustable catback. When I run without the catalytic converter it is loud and raspy above 4K RPM. When I run the cat is not as loud and has no rasp and sounds really good.

I am anxious to find out how the GMMG responds to a catless single 3" pipe exhaust system. I want to know if it gets raspy like the Borla at higher RPM's.

 

I did run my GMMG wthout the cats for a while. It would get a little rasy, and was stupid loud. I got the cats on and i think it sounds better with them.

 

Thanks for that comment, I have been thinking about selling my Borla and getting the GMMG, however I am still on the fence.

I would like to know the real reason for the raspy soun on our cars without the cat, it must have something to do with the single 3" pipe.
Anyone know?

 

When running w/out cats and especially headers w/out cats any car sounds raspy with no muffler (Borla w/out restictor plate), only a resonator (Loud Mouth), or glasspacks (GMMG chambered mufflers are just crimped glasspacks.)

 

Sorry, but GMMG is not just crimped glasspacks. It is a CHAMBERED exhaust.

I love my GMMG it sounds great at idle and WOT. There is a little rasp and when idleing down from high RPM there is some backfire but this could easily be solved with some small cats or a muffler in the y pipe. I think in the future I am going to get some small cats welded in right behind the collectors of the headers but that money now can be spent on bigger and better things.

 

Look at the chambered stick design, and look at glasspacks. They're both stick style, both with the same internal structure. The "Chambered" parts are just the space between crimped off areas of a glass pack. So if both mufflers are identical except for the dents or crimps then what else would they be except crimped glasspacks?

 

Well if they are just glasspacks, please, build the same exhaust with glasspacks and we will see if it sounds anywhere near what a GMMG sounds like.

 

i have GMMG catbakc LTs and no cats

check out this vid, at time 1.45 u can hear my car take off, and at 4.38. Its loud sounds kinda like a NASCAR car. Thats at about 6200 rpms. Theres some rasp but the video doesnt get the sound very well. Cats will tone it down, mellow the sound out and define it. Its the most amazing exhaust ever with cats. Even without but you have to hear it in person
http://youtube.com/watch?v=tt9W3weGMhc


BTW i have the white and orange 30th ann Camaro not the white and blue TA

 

I've heard both on first and second gen f-bodies with duals and they sound very similar.