To the thread.

I find the Dyna packs read about 10% high. This is because;
a, you haven't got the tyres running on the rollers IMO one of the biggest factors.
b' the weight of the wheel.

DD's run a calculation based method, this only applies in shootout 44 mode where the ramp rate is static, obviously if the ramp rate changes you cannot calculate loses from the wheel weights etc.
No methods are 100% accurate, If the dyno has a rundown test at least if you change something like the wheel weights this can be added.

Just something simple like how the car is strapped down or how the RPM is scaled can make a huge difference to the power/torque.