stay with stock gearing,,boysen tork reads work good and there cheap..open up your air box,,,drill holes in the lid if you have to,1/2in ,,and lots of them...your stock air filter will work fine,but keep it clean and oiled.shave the head .020 th,its cheap to have done.....if you can get in to the timeing your self and make it adjustable,move the timeing plate about3/8s of a in. to the left..if you can do that,you might want to venture in to the motor to port match the case to the clyinders,,and open up the intake ,,polish up the exhaust ports,,if you do that to it,,,you will have a really strong midrange power,,you will feel a big differance...i had one done like that with a fifteen tooth sprocket,front,,and was beating banshees with pipes...its a blast...