in the end its all subjective. I know about what a car should make given its setup.
you bring me a LSVTEC with PR3 pistons and ITR cams with a XXXX header i can tell you within 5whp what it SHOULD MAKE.
Just like im sure Dan knows that a supra with XXXXXXX on it should make around xxxwhp on HIS DYNO.
Ive seen from personal experience that no 2 dynoes are the same, ESPECIALLY dynojets. If you want across the board accuracy then everyone needs to buy the $100,000 Dyno Dynamics or some other load bearing.
Dynojets will always be off, they meaure rate of acceleration