Question about exhaust diameter to performance???

Diameter

Guys, I am running a milltek full turbo back system with APR stage 2+. there is no CEL errors and the sound is loud with good power delivery. However, another friend of mine is on the same software with RSC and his car seems to have a stronger power delivery.
Maybe, I should be running stage 2 instead of stage 2+ for the 2.5" downpipe.

Pls. Correct me if I am wrong.

:23:

I'll let you two decide which one is which!

I like it, the AWE vs APR "debate"! Might make a good cage match! Fund raiser!