I can't tell you why not..
But I can tell you why I did...

Exhaust, high 2 into 1 MM unit..
was to lose weight &
gain 60mm of ground clearance
even with the bash plate it still
has 20mm more clearance than
with the standard low pipes...

Kev's fueling mods were simply to make the bike
nicer to ride at lower speeds.. no surging..

Air filter.. I put a oiled foam OTR unit in.. no
power gain with it..but I don't have to worry about
water with the yamaha papper unit or dust getting
though the DNA / K&N style filters..

my bike is a XTR....


.

__________________
Harley Davidson..
The easyest way to turn gasoline into noise with out the side efect of horse power...