I recently bought a 09 600 shift 144 with 3400 miles on it. It looks great and starts up real quick! It is a EFI. I have been having some trouble with The speed and rpm first 4 weeks i have had it. I took it into the polaris shop and the clutch weights were set to 6000-9000 feet elevation. It increased its performance! but i am still have Some troubles. It's Max Rpm is 8000, and its top speed is 45. everytime i pin it, it takes off and then 2 secs later it cuts down the rpm. I was recommended to rebuild th top soon. Would this increase its performance ALOT? i need help with this. any suggestions or answers would be GREAT. Thank you.