Originally Posted by cj romeo
All it does is advance the ignition a bit to get a tad more fuel in before it knocks.
Unless you alter your driving it'll make hee haw difference.
AD's remap does give better consumption.
(Observed by cruising through france
both with and without the remap)
Went from 26 mpg before to 28mpg after
the remap. (Measured on roughly the same stretch
of autoroute , speeds between 120 and 150 kph)