I have a 2004 250 XS and my brother has a 2006 250 XS and I find his is much quieter than mine...What is it that makes the newer ones quieter ? I noticed the airbox above the plenum has no filter of any sort ... Is it supposed to ? The reason I ask is because my dealers mechanic told me to change my air filter but I don,t think mine has, or ever had one...![]()