If you have a good grip and are ready for a wild ride build yourself a hybrid quad!!
I built mine about a year and a half ago, mine is a first gen Warrior with a stock 2001 R6 engine. A GSXR 600 will be every bit as fast as mine I would think. You can read about my build here
http://www.bluetraxx.com/forums/yam...ior-87-present/80702-building-r6-warrior.html
Building a hybrid is not really that hard but it will cost more and take longer then you'd think. The reward is that you'll have fun and wicked fast atv, faster then 99% of quads on the trail. The look of the guys ridding a 1000cc Renegade, raptors, or banshee when you pull up beside them at 75mph on the ice, shift into 6th and pull away :bird: The downside on the other hand is that your arms hurt after every ride, the bike will be MUCH heavier, no deep water, no more whoops, jumps, or relaxing when you ride.
I would skip playing with any warrior rearend parts scrap the swing arm, axle, brake, shock... Everything. I found out the hard way that it will all twist and that the hub splines are too weak. My choice was late model YFZ450 axle and carrier in an aftermarket swinger. I have a thread about my rear axle troubles on here.
You are going to want to put some thought into how you want to gear it. Mine has 12t front and now 45t rear. For me top end speed was much less important then low speed control without ridding the clutch. My top speed is about 100mph but going that fast comes down to your tires and how fast you want to be going when you die.
If you want to save a ton of work, you can come buy mine. It sits in my shed for months on end. I have put 10 min on it since May. I have more toys then I can use.