My son & I are wanting to improve the performance of his CRF70. We are not ready to do any bore kits etc... at this time. Based on what we have read, it seems that we need to change the sprockets in the front and possibly the back. Also, we need to look at the intake/air filter. Lastly, possibly the suspension. I would like to hear from some of you who have done this. What we need to know is the following: 1) What sprocket sized do you recommend on the front and back? 13/42? 2) On the intake, we are looking to keep the same carb., so do we just get a Uni filter? 3) On the suspension, need something tighter on the front, and would like to know if there is a swing arm which fits the back with no mods needed? Any help will be appreciated.