Not really, I just want something of good quality and looks nice while moding it If not, I'd have got the Magnaflow and save the $$.

I had a friend running NA setup with the 1/2" spacer, Pop-charger, Stillen headers. After after the 2.5" True dual X-pipe setup with HKS Hyper canisters, the dyno showed the hp and tq curvers are better (kick in at earlier RPM) and he gained about 11whp peak. After the UTEC tune, he added another 22whp on his NA setup (his setup has never been tuned before)

No, I'm not doing for sound and look as I want it to be stock sound or similar quiet and not loud. His system is definitely not loud at all. Infact, more quiet than stock @ idle until he's at WOT or above 3200 RPM. I assume you know the OEM sound of the G35C.

My current setup is 5/16" spacer, MREV2, CAI, UR Pulleys, Topspeed headers, and soon to be a header back.

I'm still contemplating on whether I should for for X-pipe setup of 1 big resonator in the X-pipe, and two others after the split before the mufflers or just an H-pipe with Two bigger resonators before the mufflers.

The 2.5" true dual setup should be good for NA and better for FI that's under 550whp.