I have a 2008 WR450F with an aftermarket GYTR exhaust with GYTR jetting. The airbox mod has been performed on this machine (top of airbox removed for greater airflow) and it has the stock header pipe. The GYTR exhaust is offensively loud! this thing gives me a headache. If I place the old exhaust back in (which is practically silent) must I rejet? or it unnecessary because the airbox mod remains? If I rejet back to stock I am worried I will be lean because of the extra air intake.