The cat. is a fairly intrigal part to the exhaust. Remember that Hondas are set up pretty tight from the factory already.

I also believe you can get better deals on really good aftermarket for probably the $450 or not much more.

If you replace the cat., you could maybe look to do a high-flow (and get some decent power gains with all the other mods. you're talking about doing); but I would not remove it.