I had already changed the air filter when I installed the pipes. It ran great without a powercommander, but I put one on anyway. I'm running their map, no o2 senors and the bike seems to have more seat of the pants torque. No dyno, so I can't say anything towards hp. Love the sound and looks and yes, they are pricey. Only thing is the bike don't fire as fast. Before it seemed to fire straight off, but now turns a few rounds before it hitting. No real big deal, just something that happened.