Originally Posted by Maxwell
The optimum tube size is the stock set up, your not gonna gain anything, but if you want to modify the exhaust I suggest you remove the cats for a smooth pipe. This should get you about 2-5 hp more. Remember the exhaust is designed by AMG who has more experience than you will ever have.
Nope, I disagree.
Optimal exhaust setup would be.
2.5" to 3" piping, 100 cell SS high flow cat (offered by evosport), resonator removal, and a eisenmann race exhaust (or borla).