There is a photo in the gallery somewhere of an XT (may of been an X) with a turbo on it. Not being much of a performance modifier myself, if I was in you shoes I would be inclined to join the forum as an XT660 Supporter then for your 10 pound you would be able to ask Kev all the questions you need as he has done all sorts of things to XT's including Big Bore kits followed up with many hours on Dyno's to.

Good luck with it all.