A little story for ya. A buddy of mine bought a 522 RM engine this last spring. We installed it and decided to run it on a chassis dyno to nail down the tune up, so we could start sorting the suspension when we hit the track. The dyno operator insisted on running the car, and on the first pull he aborted at 6800rpm because the a/f ratio was very high (19:1). Really freaked the guy out. The car has an egt on it and it was also high, so we fattened it up 4-steps all around. Now bear in mind, the engine was dyno'd at RM in Texas. We're at 5000ft in Colorado. Next pull, operator aborted at 7000rpm. The a/f ratio and egt were unchanged, and it made considerably less power. My buddy and talked it over and pulled a plug. Black and sooty. We decided to lean it 6-steps and try again. We could hear the operator and his helpers talking about how we wer gonna burn it up. Next pull the operator was VERY apprehensive about nailing the throttle, but we finally convinced him to do it. The egt's came down to 1300 degrees but the a/f ratio stayed at 19:1. Picked up about 60 hp. Obviously an instrumentation problem.....