to me they seem a little high, but i have never compared their data to an actual true physical dyno to give a scientific answer to your question. they are a good source to have on hand anytime you want it, i would guess they are fairly accurate. they are pretty interesting just to mess around with for an afternoon. now do not laugh but this is true, I have desktop dyno 2000 and got a PS2 IHRA drag racing 1 video game, it runs the identical dyno on the game in the builder profile. i built the car to my actual super comp dragsters specs and it ran within a tenth of my actual real life dial in time on the game, hey i said not to laugh. i also did the same with my dads old gasser willys and got the same results.