i found this review.

http://www.caranddriver.com/features...ature/(page)/1

Its a bit of a read but interesting. also shows that once calibrated these gizmos do exactly what they say on the tin.
so if you have not got a track or drag strip local to you and cant find a dyno that can test our pride and joy, or just wanna play with your pals comparing each others cars you really cant go wrong.

like i said i only paid $56 on ebay for mine (brand new!) BARGAIN!!!!