Desktop Dyno 2000

I have Desktop dyno also and I've noticed exactly what Rumble says. Exact input is crutial to getting it close to what your engine is really doing. Head flow numbers and actual cam timing makes all the difference in it's readings. I remember seeing 2 different articles in the past that magazines did testing desktop dyno's accuracy (one 350 Chevy and one 440 Mopar). In both cases when they entered the head flow numbers and cam timing events then dyno'd the engine it came out real close. One was only 5 hp off. IIRC the other was about 20 hp off.