while you wait 4 him to answer, i can tell you i've tried 2 things....removal of the air duct and removal of the filter seal. The filter seal is the rubber surround that circles the filter mouth....looks like weather stripping. That w/o a doubt helps. Several others found the same thing. The air duct is part of the seat pan and most are screwed onto the base of the seat both from the inside and outside. Some found only outside screws and were therefore able to simply unscrew it. I ave to also remove the seat cover and unscrew it from the inside. Waste of time tho, as i eventually found that actually HURTS performance. So may advice would be remove the seal, leave the duct on. If someday you decide to do other engine mods then all bets are off as to what would or wouldn't be good.