Well, I'm sure that the entire R&D department @ Moto-tassinari, have done a lot of testing on completely stock motors. But for motors that are modified IE: compression change, porting,fuel choice, carbs. The 2's work better. I have made many dyno pulls and we have checked both sets of reeds on many different engine combos. Trust me, the 2's make a little more hp, not saying they blow 3's out of the water but they do make a little more power. (on a modified motor)