Hi everyone, I've got the Nismo cat back exhaust on my Z at the moment. I am going to get an up rev in the future (about 6 months away), my car is a daily driver and I really hate drone so..... would you get HFC's and release some more power or stick with the OEM cats? Also how much of a difference will the HFC's make in terms of power? How much louder will it make the exhaust? As to be honest I love the sound of the Nismo when I'm driving and it is perfect for what I want but I wouldn't mind it being a little louder at idle only.
Also should I get Motordyne XYZ Y pipe with a HFC, resonator or straight pipe? I've read that if you use test pipes and then the HFC on the XYZ pipe then the car will still fail emissions tesitng and so I wont bother with that. If I was to keep my stock cats and then use the resonator on the XYZ would that sound good and not be too quiet? Or should I stick with stock cats and straight through pipe?