The stock exhaust system is 2.5" with high flow cats already so theoretically you should only need to change the mufflers and tips (axle-back). (until you're pushing more than 500 rwHP.) The reason the mid-pipes change the sound so much is because most of them are O/R and don't have cats.(which won't pass inspection)


JLT II -28-34 rwHP on 05+ GT

http://216.119.83.47/proof.htm

 

The stock exhaust is 2.5" but it does NOT have high flow cats ... No mid muffler exhaust system deletes the cats, it doesn't even include a mid pipe, it's just from the mid pipe back ... The JLT's 28-43 rwhp claim is WITH a tune since you must have a tune to run ANY of their intakes.