they do work I tried one in my car when i still had one :(
it was 5mph faster at 4000rpm through all the gears the main use for these things is in drag racing where they are only used for short amounts of time.
If you use one on the road for extended periods as i did your ecu will adapt itself to the chip and will start to idle too high and the revs will surge when you lift off the throttle.
it took months for my car to return to normal after i took it off :(

An electric box of tricks cant possibly make a car/bike go faster for a particular number of engine revs. Revs equals road speed, the only way this can be changed is to change the gearing. It might get to that speed more quickly though.