Got it. You may want to post your mods in your signature so that everyone knows.
I say keep your options open, and try to find a used OE catback/replacement third cat to gut, so you have the original one for use in case you need it (never know if regulations/testing could change).
Other option, and possibly easier, cut out the third cat yourself, which I assume you have to do to gut it anyway.
Put exhaust clamps on both ends of it, either weld your own setup, or use the kind that come with an axleback.
For your regular use/non emissions testing, clamp in/bolt in a set of straight pipes.
For emissions testing replace the third cat.
That is what I plan to do with mine, since shops here will not cut it out and replace it without keeping it and legally can not delete it. This way, the shop is in the clear, since all he is doing is making an "off-road/race-use only" exhaust piece for my car, but putting the stock cat back in.
Hope that helps you out.