My RK has a Power Commander, Vance & Hines two into one Pro Pipe, and a Kuryakyn Hi-5 air cleaner. I had a custom map done on the Power Commander, and the dyno says I'm making 75 HP, and 80 foot pounds of torque.
When they did the custom map, I told them to set it for best MPG, rather than try and get all the power available, but it still was only getting 38 MPG when they got done, so I started playing with the mapping myself on my computer. When I finally got it where it seemed to be working the best for me, I had leaned the fuel/air mixture about 12% in the mid range (2600, to 3200 RPM), and 8% everywhere else. Now the motor feels stronger, it's getting better gas mileage, and the plugs are a nice tan color.
FYI I like to get down and boogie, I don't beat the crud out of it, but I don't ride easy either, My floor boards are always throwing sparks in the turns.
Thanks for the info about the rough ride with the lowered suspension, I was thinking of putting a lowering kit on mine. I haven't because I don't want to give up ground clearance, but if it's going to ride that bad, that's even more reason not to.