I have the BMS PBX for over a year now. I was very very impressed initially. Through time you become so accustomed to the new throttle response that you begin to want more again. What I do to remember what a huge improvement the PBX is over the stock throttle is that I disable it and ride around for a while in agony. Lol
I do suggest if you buy a PBX buy used. Plenty out there second hand for $100-200. $300 like I paid isn't worth it. Put that money towards the PE. Now with that I AM HAPPY!
By the way, also look into the AA tune. It is the only proven (through dyno) mod that will gain HP. I've read some very good reviews on it.