HEMIJAKE
Ram Guru
Depends on the vehicle, but some see decent improvement. When I was messing with s550 mustangs a few years back, aftermarket pipes made good numbers, but that was coupled with good tuning as well. I feel like they go hand in hand. I went with aftermarket catted vs. catless, but that was mainly just for visuals. I could have probably had a buddy inspect it without, but I didn't want to have to rely on it. And the aftermarket catted was almost as good anyway. And you're right, you could just knock out the stock, but in my case, the overall piping was bigger diameter, so that was a factor for me as well.Could just knock the guts out of the factory cats. Cheaper ways to do it. If there is no sniff check, then it doesn't matter. And most aftermarket high flow cats won't even pass sniff test, and don't even help performance that much