I put a set of XiEDs on my 2007 Fat Boy after installing the Screaming Eagle SP slip-ons and a heavy breather kit. They worked great for solo riding, but the didn't quite do the trick when my wife was on the back. A bunch of my riding is done two-up, so I sold them and bought a PCIII. If I didn't have my wife on the back all the time, I would have stuck with the XiEDs.

 

I've been using XiED for over a year w/o problems and no tuner. Do what they say they do!!