I've had mine for a few months and have only managed to put about 500 miles on it so far. I have the V&H ProPipe chrome, and a K&N Street Metal intake. Runs great with no decel popping. I plan on doing nothing else to my engine. I only cruise around and rarely do any full throttle acceleration. I will keep this setup for as long as I own the bike. Found one on an ebay shop brand new, sub $200....

 

Depends on what you plan on doing to the engine and how you want it to run.
I had one when I was running big shot staggards and a a/c. Still had surging and popping at low rpm's. Found out the fuelpak only adds fuel when the ecm is in open loop mode. So I added xied's to smooth it out.
Changed pipes, changed cams and the fuelpak became useless.
If you want your bike to run its best invest in a good tuner and a dyno tune. After I had my bike tuned the difference was amazing!