RT: You can change the exhaust and install K&N carb jets. Go with a hypercharger if you want to spend the money. You might get an extra 10HP but I don´t think the flame is worth the candle. Best bet is to go with the K&N jets and air filter. Horsepower increase won´t be all tht much but warm up and acceleration will be an improvement. Haven´t heard anything about gong to a 900CC engine, but keep in mind that the bike is light and would probably be overpowered.