Hey all, I have a question about the GMMG exhaust. A couple of weeks ago, I had my Z28 in for an oil change, and the dealership had a Silver Stage One (Joe Gibbs Memorial SS) ZL1 super car in the showroom!!! Anyway, I wanted to hear the chambered exhaust so I asked them to fire it up. OMG, was that mother loud. So here is my question. When I sat in the car, it was too loud to even talk to the salesman that started the car for me. Is it that loud on a stock car? How about on one with cam/head mods (I am planning to do this in about a year, when the warranty is up on my car.) BTW, we were in the showroom when he started the car, and we never left, so I assume that made it sound a little louder. Thanks!

 

hhhhhmmmm.... you are scaring me a little.... I have never heard it in person so hopefully a couple of guys will let us know for sure!This is the exhaust I am planning on getting for my car, I was under the impression it was not that loud. (did you give it gas?)

also it all depends on what set up of heads and cams you are planning on getting. the more extreme you go the LOUDER its gonna get and I mean loud. But if you are getting more of a stock idling and sounding it wont make that big of a difference, esp. when just cruising.

Have you heard the clips on there webpage?

anyways hopefully someone will speak from first hand knowledge.

 

Yeah, the exhaust did scare me a little too. It sounded great, but it was hard to carry on a conversation. Like I said though:

1) The car was a stage one ZL1 w/ 400 hp

2) We were in the show room.

To answer your questions Swingdriver, the salesman did not give the car any gas (out of respect for the receptionist sitting near by). I heard the clips on the website, and they sound great. As for future mods, I just plan on going with some head porting and a more aggressive street cam (LS6, or maybe something for LGM). Thanks.

 

It can't be any louder than my headers, X-pipe, and Dynomax bullets. I don't find mine difficult to deal with at all, but everyone has their own tolerance.

 

Its not as loud on my car as people make it out to be. I've heard that if you add headers and no-cats it will make it unbearable. My car is all stock until after the y-pipe.

I have had numerous compliments on the sound of the exhaust. Sitting in a fast food drive thru, the guy in the window was telling me that he liked ohow quiet it was at idle. I have to agree, at idle it sounds good, not too loud, but an awsome gurgle sound out the back. On the highway doing 70'ish, it does growl a little. The noise on long trips is a little much, but barable. Just turn up the radio My favorite is Wide open, or just getting on it from a stop. Sounds awsome, car really wakes up.

On the other hand, some of my friends say it is loud when Im driving off. I never have heard it from the outside, so I cant really tell. As far as I know, its just right, sounds like it is suppose too.....and it really shuts up those pesty mustangs :P

Its impossible to describe the sound of the car with an aftermarket exhaust. As far as what I have heard, it sounds 10X better than the loudmouth, but its not as loud as it. The loudmouth has a lot of rasp and poping that the GMMG just eats up and produces a nice low rumble at all RPM's.

The thing is expensive, but well worth it. I wouldnt have it any other way. I love the way it looks and sounds on my car. As far as the ZL1.... not sure what else was done to that car to make it so loud you couldnt talk to the guy in the other seat. My car is a convertible and its just fine, even with the top down.

 

we have a customers car here in the shop that we did a heads and cam swap on. the cam is a 224/224 Comp Cams with .581/.581 lift and a 114LSA and through the TTS headers and GMMG exhaust it is still fairly quiet, nice and deep throaty sound but not what I would call loud, but I was running my car with open headers for a week before we pulled the engine.
But my point is I don't feel it is all that loud.

 

I rode in a SS with the centered mounted exhaust with the GMMG and it was quiet inside at idle and around town. On the highway at 2500 rpm it drowned a lot but not any worse than my flowmasters do on my mustang. I decided then I didn't want one because of the drown. That gets old very fast. I don't care for having my ears ringing during long drives. If I didn't drive the highway I would then get one. I think they look awesome from behind.

 

Who needs a radio when you have the GMMG exhaust, I love mine.

Al

 

The 400hp ZL1 you heard has the LS6 engine, whatever kind of exhaust manifolds the LS6 uses, and out the GMMG Chambered Exhaust which you heard. Really shouldn't be any louder than an otherwise stock LS1 F-body with this exhaust. It was probably really loud when they fired it up because the engine was COLD. Cold starts are very loud until the car fully warms up, in which case the motor becomes a lot quieter at idle.

BTW, I had the GMMG on my last LS1 and I now have it on my newest LS1 if that tells you anything. Both car's have been mostly stock and this exhaust is kinda quiet at idle, definitely noticeable while cruising around, and growls extremely loud at WOT. Basically, you hear it the second you touch the gas, and it only gets louder as the rpms rise. And whoever said it drones doesn't know what droning really is. This exhaust has NEVER droned on either of my LS1's and I've had the SLP Dronemouth as well(that exhaust would give you a headache inside the car).

Outside of a good true dual set-up, this is the ONLY cat-back I'll run on my LS1.

Mike

2002 M6 Z28

 

Thanks a lot for your replies. I had a bad experience with a droning SLP once, and I didn't want to repeat it. It sound like my experience was unique. I'll probably give the GMMG a try in few weeks. It looks incredible. Thanks again.

 

I have had the GMMG exhaust on my car for almost a year now and I still love it! I wouldn't consider it loud though. A nice deep tone and bearable. If you want to hear what your exhasut sounds like while ur in the car. Open the trunk up a bit. I had to have my mountain bike in the back one day and the exhaust sounded so damn good!! My trunk was open probably 6-8 inches. Give it a try!!

 

i have a custom setup with sweet thunder chambered mufflers , and its actully a little louder than gmmg, sounds almost identical, had the cars side by side, i dont think its all that loud really, out back yea but can be alot louder

i have video but no way to get it on computer or id post it

 

Check this out: http://www.onehotz.com/Modifications_Pix.htm

That is GMMG exhaust with dual tail pipes. Is this offered by GMMG? I havent seen them on the website (just the premium tips). Thanks again for all the input.

 

Those look like the Fast Toys Dual Tips. I have them on my car as well. They are nice quality tips from what I've seen with em so far.

 

the gmmg is just as loud as the loudmouth just deeper in tone.