I would like to make my own gmmg and need alot of help. Could some one tell me what size pipe that goes to the I pipe, what bends should I get , what Y pipe to use.

I will be using 2 18" sweet thunder 2 1/2 in out mufflers and slp 2 1/2 dual tip.


Going on 1998 formula ls1.

 

You mean a chambered exhaust. GMMG is a manufacturer and they have a patent on the system. Contact badpewterz, he built a custom chambered exhaust a while back and has pictures and a list of materials, I think. He is on this board. Yeah, we owners of the real GMMGs are protective. Do search using "custom gmmg" and you will find alot of info on this.

Good luck on your project,

PJ