I like my 07' YZ450F, but the bottom power sucks compared to my frind's 07'CRF450. QUOTE] I felt the same way. I rejetted with the JD jet kit and got the bottom end I was looking for. I also got tons of mid and topend I wasn't looking for. I went down one tooth in the back sprocket and now love the power delivery to the rear wheel. I got what I was looking for and can control it well.