Guys I talked to mickey Dunlap of FST, the idea behind the clutch cover method is the just recently cooled oil goes directly to the crankshaft bearing were it most needed, the bigbear setup has to go through the motor first picking up heat again before it reaches the crank. The bigbear cooling assm, was designed with a 4x4 in mind that would see some hard service and was designed to help cooling overall. It's a mistery as to why Yamaha never put a cooler on the Warrior or for that matter a Raptor 350 from the factory. Use what you want and are comfortable with, I just perfer to use what a racer designed and uses himself and has backed his findings up well.