Just curious....anyone have dyno numbers or track results on GMMG catback system alone?

 

I've heard that they flow just as good as the big name brand mufflers - just a different sound.
So one could expect to see exactly the same numbers at the track.

 

The GMMG was the first mod that I did to my car. I gained about 5hp with the GMMG. I gained about another 5-6hp opening my cutout. FWIW

 

I dynoed this past saturday. mods listed below in sig. Well the SLP lid w/filter is good for 7-13rwhp, and the other stuff won't make all that much difference so the GMMG gave me anywhere from 9-13rwhp, i would lean toward the 11-13rwhp though for just the GMMG cat-back. My total gain from stock to with mods was 24rwhp. hope this helps.

And by the way you can't beat the GMMG sound quality.

 

This dude is right! I went from a bone stock dyno of 298rwhp & 320rwtq @ 1,263 miles to 323rwhp & 342rwtq @ 2,057 miles with ONLY the additions of a Direct-Flo lid & GMMG cat-back. That was a total gain of 25rwhp & 22rwtq with both of those modifications. As you can clearly see, the GMMG Chambered Exhaust is probably worth around 10-12rwhp on a stockish car just like that other guy already said while the lid is "known" to be around 10 or so rwhp itself.

BTW, both dyno's were done at Speed Inc and the #'s are SAE corrected.

Mike

2002 M6 Z28

 

i can vouch for speedys numbers, i was there. remember on an SS or WS6 they already have a 3 inch exhaust so the gains from GMMG are less, though still impressive since most catbacks (b+b comes to mind) only dyno 2 or so rwhp. non SS or WS5 cars have 2.75 inch so the gains are better. cant beat the sound either.
brian

 

Yes sir i tell no lie. SleeperZ96BT was definitely there to witness the results. So thanks for that back-up post Brian.

 

Anybody have LS1 w/GMMG system sound clips? I don't want an exhaust system as loud as an F-150 with glass pack.

 

Have you heard these sound clips yet? There from another member here on the board.

www.cobraeater.cz28.com/Exhaust

And this exhaust will probably have the same volume as the Flowmaster did on your LT1(although louder in the higher rpms) but without that awful drone.

 

The GMMG is definetly one of the best sounding exhausts for the f-body LS1's besides True Duals.

 

I think its the best sounding Exhaust for the Ls1. Talk about an Intimadating growl

 

Ouch!!!

 

this man speaks the truth I'm surprised more LS1 owners don't go with true duals...especially considering the $$ of the GMMG. Unfortunately I don't have sound clips or dyno numbers to compare, but the sound is NICE.