Hello; I guess it depends how you measure power, a 70 surpass will spin a 14 x 6 prop around 10,000, a 46 two stroke could never do that. A good 46 will spin a 10 x 6 prop pretty near 13,000, maybe even more. A lot depends on teh plane it's going into. My choice would always be teh four stroke. One of teh problems with four strokes in teh past has been the extra weight, Saito has done quite a bit to lower the weight to power ratio lately.