Has anyone used one?

I've heard pretty good things about them.

I think as long as you can get your vehicle's weight, they're supposed to be pretty accurate.

I would like to have run a couple of comparisons before and after I did some of my little mods (plugs, air cleaner, etc.).

I've been thinking about trying to upgrade my brakes and thought it'd be neat to see if there was any improvement in stopping distance.

Just curious.

My buddy has one. and I've tried it on my cars and it seems to be pretty good. There are factors that can make it wrong but most part it's a good product.

you enter the weight and it sets the angle of the road and stuff, it also calculates in most part the HP of the vehicle.