The 2006 had a velocity stack as standard in the tweaked airbox, the parts can be bought as a kit from a member of this forum for the princely sum of approx £35. These when fitted with a plennum spacer and tuned and uned with Up-Rev have given slight hp raises over the standard airbox and pod filters which pretty much just give you a bit of induction noise. As GMBallistic mentions, the previous problem with pod filters is that they suffer from heat soak, thus losing a little power. Bizarre as it may seem, a K&N, '06 airbox or '03 to '05 fitted wth the velocity stack kit is the best way for you to go.