I have the Slim on my KP. Works great. However there is a cheap bolt on kit to add the Fats, and I have the Drop Top as well. All I do is pop 1 off and toss the other on.
But I have inverted forks.
I do not see much difference at normal speeds, except at higher speeds the Slim actually keeps more air off and wobbling down.
Torque Tubes, VM-1 cams, PCV, Throttle ring, ATS