I have one for my Harley. Basically there's 2 types.
Those that piggy back the ECU and fool it into doing what you want and those that actually re-program the ECU. I went the reprogram route with mine.
Now this is a low tech, 103 inch, NA, 2 cylinder.
I immediately notices a MUCH smoother running bike, lower temps (it adds fuel - lean is hot, rich(er) is cool) and I went from 41 mpg all the time to nothing less than 45 mpg with 54 mpg a few times on leisurely runs with the dealer group. I expect to LENGTHEN the life of my engine because it's running cooler than before.
There's a gold mine of performance to be found in most anything electronically controlled - if you're willing to run with scissors.
