Like someone already said in a nother post on that subject. This plane was made for the 11lbs trust Sophia...The New Kangaroo2 is lighter than the old one, so anything from 12 to 20 is ok. I think you get about 130-140mph with a 12lbs...Anything asbove 20 is overkill...But it's seem to be the new tendency to overkill everything ( sevos torque, engine trust ect...)