You could always put on a pipe. That always boosts the power a noticeable amount but remember to get a pipe that fits your riding condition. I personally have a gnarly pipe and powercore 2 silencer. It gave my bike a huge hit down low, and the pipe is nearly indestructable. If you want quick engine responses, you can get new a new reed valve cage. I have a the v-force 2 and it made response VERY fast. It doesn't increase power too much so you may not want this unless you ride fast and hard. Like the others said, revalving the suspension, new tires, and new handlebars can really help. I don't know if you have jumped or not, but the stock bars are not very dependable if you over jump a landing.