A few years ago I used both DD2000 and EAP for estimates on a big block to compare the two. I had an engine that was going on an engine dyno anyway so I thought I'd see which was more accurate in my case. I was very meticulous with inputting specs in both programs. When all was said and done, DD2000 was off by 36 horsepower and about 20 lb-ft. EAP was spot on (!) with the horsepower estimate and was off by 7 lb-ft.