did it on my ls1 before the headers and duals. I just took out the stock muffler and put a pipe in, kinda like camaro69's but a bit more flowed without the t-piece

I havent lost any gas milage either, to be honest I cant tell the gas difference now and have headers and true duals, no cats or mufflers etc etc

 

well i know that i had a big fckin hole im the muffler in my tbird and my gas milage dropped to like 11 from 22

 

hm that is different though. thats more of an exhaust leak or something. i will go ahead and do it. i appreciate it you guys. ill post tons of sound clips and what happens before and after on this thread when i get it done end of month.