Originally Posted by semtex

Mmm...not sure I'd say the HFCs make it worse. I was speculating that the HFCs were the root cause. But I think that's now been proven wrong. If RCZ is experiencing the issue even with stock cats, then it's not the fault of the Berk HFCs. It's the Stillen exhaust itself that has the issue. I'm about to send a PM to Josh to make him aware.