I agree but here again, use the figures as stated by manufacturers and prop the engine correctly and get the ratio between 5 and 8 pounds per "rated" HP and you will have good power. If you like a little more power, aim for only five pounds per HP. Look at examples of models from .40 size up to those 1/3rd scale jobs in Europe and I think you will find most models when correctly powered will fall within 5 to 8 pounds per HP. Again I am talking single engine fighter types. From a full scale P-51 down to a Tower Hobbies AFR 51 - all will fall within the range.