[kscoyote]

Can someone please explain to me what a h-pipe/x-pipe is, and what they do? I have seen them around some websites.

they equalize cylinder evacuation.

 

[kscoyote]

If I get a h-pipe should I buy them with the cats?

yes, cats don't impede flow, the danger is flowing too much.

Keep the cats, and you won't have to worry about a $1200 ticket. + the costs of the cats anyway.