I have Performance Trends Engine Analyzer, I use it a lot, but I generally dont pay much attention to the gross numbers, as they are usually about 5% high, and Engine Analyzer is considered one of the most accurate. However, it IS an excellent tool for balancing static compression & cam timing to try to zero in on the maximum dynamic compression ratio that your local pump gas will tolerate, or seeing the effect a change will have on the SHAPE of the power curve, or if you want to go to a bigger cam but maintain your cranking compression, it can be a useful tool for figuring out how much to tighten the lobe separation. But as far as generating gross numbers, I dont generally use it for that.