heh i got an etrex off ebay for like 36 dollars a few months ago for this purpose got my ultra comp up to 49mph with a 15tooth and my axial .28.. its pretty cool to do also lets you see the small differences the ratios make when you change the bell... i have a new buggy but with the same motor and such so i haven't bothered to mess with it... but thats funny you did the same thing with the same gps..