Ketchmi

An X-pipe replaces the cats, there are high flow cats available to install on the X-pipe but the factory one are removed for the X-pipe installation.

DKWalser

I stand corrected (or sit, as I type this). In an earlier conversation, I had misunderstood that the X-pipe did not require removing the stock cats and that high flow cats were available to replace the cats if one desired an additional power increase.