Weight makes almost no difference to Topspeed. Think of it this way 100metres gained at the start because of superior Power/weight/grip is only 1 second extra on the throttle down the other end at 200mph. The least Power ive seen to pull 200mph at Brunters is circa 650bhp in a Porsche with good aero. For that reason I never compare different makes or even models of car you cant cos there aero's are different & thats what soaks the Power.