I have searched the forums and it looks like most recommend art pipes. I just put the MD Shockwave V2 with stock cats on my G35 Rev Up and really like the sound. The installer recommended Berk HFC and most searches on the forum recommend art pipes. My installer said the art pipes, he installed before cracked and posts keep talking about rasping with HFC. I want the sound I have right now, but I want to know how much power/torque am I giving up by keeping the stock cats. Any help is appreicated. By the way, I must replace my cats because they are going bad, so I have to make a decision on which way to go soon.

 

110% art pipes.

 

Well, lucky for me from before and after for the HFC it was a gain of 15 HP to the wheels. I hear TP give you another 5HP on top of that