i have a k n airfilter is it gonna be ok to remove the lid and rejet the carb and what is the bennefit of doing this and how many jet sizes do you go up to do this
Hell yeah. My '04 won't even run with the lid on anymore now that it is jetted to run without it. This is one of the cheapest upgrades you can make. I only use the lid to keep water out during washing.
You might want to grab an outerwears for it though. A lot more (and larger) dirt comes in without the lid.
K&N is fine as long as it is a REAL K&N. I had a cheapy look-alike once that acted plugged when freshly washed. What a POS. Real K&Ns flow very well. The foam styles are good too, though. Uni, No-Toil, etc. They are all good.