My cat is bad and my cat-back is rusted out so I need to get new of both...was looking at the ZZP SS bolt-on DP w/cat and a magnaflow cat-back. I don't plan on doing much to the car in the near future so would 2.5" be OK or is there really a need for 3" on the DP? I'm looking for something that is near stock sound-wise so if anyone has any advice that'd be greatly appreciated.