From personal experience, if you are in fact going with that exhaust, you have a couple options. If you want LTs and want it to bolt up 100%, go with the xforce longtubes. They are 3/4" vs 7/8", so keep that in mind, but I have them and the fitment is great. I'm very pleased. If you don't mind not having LTs but rather mids, go with some Kooks mids, they'll bolt right up. If you want LTs but 7/8", you will have to get a little custom. I should have bought the LTs when I bought the exhaust, would have saved time and money. I'll say that for the cost, if I had to do it again, I'd have gotten a set of ARHs from the beginning. I like the xforce, and for a full 3" the switchable mufflers sound far more docile than the setup would have with the stock GXP mufflers, but considering how little I drive the car now relative to how much I had expected to drive it, I would have lived with it until tracking down some GT muffs. Good luck on your choice.
-J