High Flow Cats
 

I see Circuit Works has High flow cats with the O2 sensor bungs now. I was thinking of going with a set of headers and the high flow cats this winter. I'm also planning on using my stock (Crios Mod) S muffler. Do you guys think I will notice any HP improvement or I'm I just wasting money? My car is a 98, non S, one set of cats, stock intake.

You meant cat delete pipes from CW?

No I mean High flow 200 cell cats. They sell them on ebay. The pics don't show the O2 bungs, but the description mentions them. I emailed the seller and he told me they do indeed have the O2 sensor bungs on them. Since my car is a 98 I only have 2 cats instead of 4 like the later models. Circuit Werks Porsche Boxster 986 2 7L 3 2L High Flow Cats Catalytic Converters | eBay

I have the stainless exhaust manifolds with no cats and a pair of 100 cell cats. The exhaust is modified internally by Carnewal. Sounds great and released a few more ponies.

I should add mine throws a CEL for cat efficiency as the rear lambdas can't keep up. I've tried the lambda spacers. The car passes MOT emissions no problems.

Well if I could get a little quicker throttle response and a little better sound it might be worth it to me.

Depending on what you mean by throttle response then you might find a custom map will help instead as they can adjust the throttle request map amongst other things.