A lot of times change is a good thing ! I have seen many people be fast with the Impulse , and just as many struggle with it . Can't really say why , maybe the window on tires has to be very specific ? I had an '08 Tempest and to this day regret selling the kart - it was the best kart I have had to date , but got myself a Vortex and we will see what this kart does when I hit the track , but it is suppose to be very user friendly with a good size window on different brands of tires . Good luck to you with what ever route you go !!