In-season Summit models include the Highmark and Adrenaline. Highmark models are RT-platforms with the 1000 SDI, where Adrenaline models come with the 600 H.O. SDI or new 800R PowerTEK. Highmarks are 15 pounds lighter; they ditched the rear rack and extra seat weight and get the Challenger Lite. Adrenaline models also have the raw rear end look, 800s get the HPV roller clutch and they all get 2.25â€ lug heights. Suspension changes (last year) make them the best all-around mountain sleds, and for 2007 the 800R Summit Adrenaline is tough to beat.