I have a DP Ultimate and and originally had a YS 120 on it with a APC 16-8 prop and it was awsome in all areas but one.It would just hover (hang on the prop ) with not much pull out.I swapped to a Saito 180 with a APC 18-6 and hang on to your Transmitter! It had unlimitted vertical and honestly I could not tell any difference in flying because of the heavier motor.That plane is great.It won the Biplane shootout in MAN a few months ago.Nowto the big drawback to the Saito 180.Ihad to put an additional tank which brought it up to a 24 oz. cap. to get a comfortable 10 min. flight.That Saito loves fuel!The inverted flatspin is very flat and descends slowly and looks great. Dave