The Thudercat is electronically governed at 80 mph. It is deffinately the fastest hands down. Of course I have not ridden one but have talked to an owner of one, and he said it is not at all for a novice rider and it is crazy powerful. Any article I have read on the T-Cat says the power is above any other offering on the market. My neighbour has an Outty 800 and it is by far the most powerful quad I have ridden so far, I loved it.
The T-Cat has a spike load dampener in the drive line (a clutch pack saorta thing?) to eliminate twisting things apart like axles and diffs. Must have some power
950 V-Twin efi, 188 lbs tourque... should be fun.