I don't know.. It could be.. I watched some people test them, and they claimed that a good high flow cat won't bother the exhaust flow untill a certain point. But it feels like it.

I think it depends on what I do. I could use a ebc to try to keep boost up. Or raise the boost so it spikes to 33psi and lowers to like 27.. Then just take a degree out where it spikes to be safe. Either way... If the exhaust is the problem it shouldn't help much..

I don't wanna remove the cat.. I like the mild bolt on idea.