Oh its accurate, we tested it in jason's car, and it was a few milliseconds off on his 1/4 time, as for his horsepower, we entered his weight and it was very close to his dyno HP rating. Same with wolf, as for me, i know my weight so mine was 145HP when i made 149 on the dyno. And the weight only affects the HP, u cant change physics and gravity, you actually ran a 15.9 suck it up.