what I find, on this, and the HD forums as well, is lots of talk about increased power etc etc etc etc... What I do not see is EVIDENCE for any of these claims.
For some evidence, check out the power and torque curves on the Garage 56 web site for their Stage 1 kit
here.I can confirm there is a noticeable performance improvement from this kit, based on my seat-of-the-pants gauge.