I have dynoed the plates on a 602 gm crate motor and 650 holley. Circle track application. The customer said he had a hesitation when picking up the throttle. Someone recomended the plates to him and he tried them. He said they fixed his problem. I was skeptical so I tested with the plates first and saw no hesitation. Next I removed the plates and noticed a hesitation as I picked up the throttle when testing . Also I noticed it made more power without the plates. I think it was in the 3-5 HP range if I recall correctly. That's Average HP from 4000 to 6200 rpm on a motor that makes around 350 HP. peak. I checked and the nozzles were aimed right at the boosters. So to double check I repeated the test and got the same results. The plates seem to cover up the lean spot with less fuel. Unfortunately they also seemed to restrict air flow through the carb at wide open throttle. Not to surprising as they take up alot of space in the venturi. I ended up increasing the nozzle I think around .004" and fixed the hesitation without the plate and kept the power. i might have left the plate in on a street application where mileage was more of a priority than the 3-5 HP gained.