Got a chance to test drive a 400 with FIS!!!! That FIS system worked very well over a tree stomp. Salesman said that the 500 would be a litttle more powerful with a ditigal gauge. I also read in ATVAction where they couldn't get the A/C stuck in the mud. Suzuki, Yamaha, Polaris, & Bombardier all just stood behind the mud king!!! Impressive!!!!!!