LOUGHBD Now that heli's are more popular and special fuel is stocked for them. Flyers are grabbing the 30% trying to make their 4 stroke perform like a YS super charged. If YS had'nt started the 20-20 craze the bulk of engines would still be on 10-15%. I personally think the extra oil in 30% HELI makes the nitro less potent and a 20-20 YS blend would be about the same. Look Americans invented musle cars but we limited ourselfs to go in a straight line.