Willis, your quad 04/05 or 06 and newer? The info listed below is for 04/05.
I think the kit is a waste of money. It will come with a lot of stuff you won't use. I would just get a cam and if you wanted to go deeper get a higher compression piston. The HRC kit is around $300. I put an 02 CRF450 dirtbike cam in mine and a 12:1 CP piston. My quad pulls on Turboderf's sons with that set up. The cam was $177 and the piston was $185. The HRC kit comes with a cam, semi open air box lid, main jet, needle, exhaust end cap and different snorkle. I choose the 02 CRF cam because it has power from bottom to top. If you don't want to do a piston I would just get a cam. Here is a link to help you choose a cam.
http://www.trx450r.org/forum/index.php?showtopic=51082