O/R H-Pipe OR De-cat

If you gut the cats, you may get some turblent air due to the shape of the hollow cat. With an o/r setup, the pipe doesn't bulge out, it's a consistent diameter.
 
Youll probably end up spending the same in the end. The h-pipe is like 150, and you'd have to pay a shop to gut the cats, cut them out. Weld in pipes and reweld the cats back on. Its pointless.

Also, the stock midpipe is only 2.25 in diameter and the Mac H-Pipe is 2.5, so youll get a nice power increase as well