Anyone running one of the K&N RK Series air filters on an otherwise stock bike? They claim a max HP gain of around 8HP at 3700 RPM with no fuel tuner needed. I understand this will make a stock/lean bike a little leaner without adding a tuner but I just don't have the finances to do the full Stage One or even the tuner without my wife throwing me out of the house! I've got to take the air filter off as part of the 10000 mile service so I figured it might be time to replace it with something better.