Are you asking about the gizmos that can be added in series with your 02 sensors to change the reading to the ECM and make the injectors stay open longer? If you are, I had a set put on my bike at Bike Week a couple years ago and they do keep the bike from running as lean. I can't see any difference in mileage and my 2012 Tglide isn't producing any codes. The bike does run smoother and produces a little (and I mean a little) more power. You're not going to be able to feel any less heat on the outside of the engine. The few hundred of degrees it reduces inside the combustion chamber isn't going to be noticeable outside.
Once I saw what it is, it's easy to install if you're half way mechanically inclined.
PC