I have the same catback on my turbo civic, I'll upgrade to 2.5 piping soon though with a hi-flow cat. I think i'll do the install right at the dyno and see how much of a gain I get with a magnaflow high flow cat and 2.5" piping from the cat since the downpipe is already 2.5". Only problem is my catback piping is 2.25" and if it's changed to 2.5" someone will need to bend the piping to match the catback piping and weld it.
This exhaust really does sound great, i have a crack in my downpipe so it sounds a little off right now. I'll post a video soon.