Hey Daniel - the first is a decat pipe 3" the second cat in the photo's i sent is this -> "metal matrix 100 or 200 cell one, around 4inch core, you'll probably get good results from a change there"
As I said earlier in another post on this subject in the ACT section. Cats are genrally not the issue in restricting air flow (that is if they haven't collapsed). The muffler is
All this stuff about Catalytic converters and cfm ratings is mostly BS from people who wish to sell you there product.
Decat is obviously better as it has NO internals so absolutely no issue - EXCEPT it breaks EPA regs.
@250 kws with your decat (cat with the guts ripped out) and turbo is NOT your issue. Add 100kws to that and then start thinking about restricted air flow.
I'll go measure both internal diameters if I really have to. Tis better if you just come check them both out.