I used a product like this on my F.I. Sportster a couple years ago, it worked. What it does is trick the ECM into running a bit richer by changing the imput to the ECM. The only drawback is that the computer can only be fooled when it is reading the A/F ratio, not when it's running on the map. Closed loop/Open loop. whatever, it helped the idle and maybe cooled down the running temp just a bit.
