Actual ZL-1 Horsepower.

[GRB]

Does anybody know if the GMMG chambered exhaust is as restrictive as the OE GM exhaust? If it is I've got to start making plans to get the GMMG system off my 02 ZL1. Since I last posted we have decided to put a SC on the car. Of course when we dyno the car with the Kooks headers open and then closed we will know for sure. Something tells me we should go ahead and plan for a different exhaust system now. Any thoughts?? And I don't care for the duals that dump over the rear axles. Gotta go all the way out the back for me.

[SMGCO]

I don't think there is any comparison between the old OEM chambered exhaust and the gmmg chambered exhaust. The old exhaust was crimped at the bends and was down to less than 2" in many areas. Our gmmg exhaust is mandrel bent ( ie, smooth bends ) and fits perfectly. Call Murphy and discuss it with him. He thought everything on our cars through with ultimate performance in mind. However, you might want to talk to Porterfield out the dual cutout he has on car #1. Barry at Quick Time Performance can help you also.
What rear end gear ratio do you have in your car ? The 4.56's in mine really woke it up. Any more power and getting traction is not possible without drag radials or dot slicks.

Regards, 02-#47 zl1 ( c5r )

[Chevy454]

I visit quite a few LS1 sites, and they all seem to rave about the GMMG chambered system. In fact, they're doing a group purchase over at LS1tech right now. Everyone used to want the LoudMouth exhaust, but now everyone seems to be ditching it in favor of the GMMG.

The GMMG chambered is nothing like the restrictive chambered on the first Gens...in fact, when I was replacing the chambered on our '69 I looked into trying to retro-fit the GMMG system.

Are you still running the 10bolt?