I'm of two minds on this one. Had a FP on my 05, zero issues and ran great. Have one now on my 08 FB, and getting some occasional deceleration popping, but overall I'm still satisfied, except for the lack of room to place it.
I had a run of fuel paks take a dump on me. The ones in particular was the XL/200 tire softail version. I refuse to install them. Total garbage. No where to put them in, other than butchering up your fuse block.
Race tuner, no fuel pak, no PC III's. I have had fuel paks and power commanders, won't buy them anymore.
I'm going to throw a monkey wrench in the mix and say get a ThunderMax w/Autotune. Once you get it in you can retune it just like the Race Tuner, but with the Autotune it will continually fine tune itself. So you don't need to have it dynoed everytime you do something to the engine.