ive gotta g-tech...its semi accurate...about .2 faster and 2mph faster......i tested it on a track in orlando 6 times to get these figures. i got mine off ebay for like $50-60(it came free with tires for the guy) and i dont use it enough to justify buying it, but keep it just to say i can use it if i wanted/needed too, and soon i will need too .

Brandon