HI there, I just did the maiden on my 330s today and was very pleased with the results. After reading this page I was a little afraid I had missed figured my power to rate ratio by putting a tower hobbies .61 engine on it but found that it performes extremely well. It will pull straight up and go out of site. It does all of the pattern manuvers at half throttle. I see no need for any more engine. I am using a 11X8 prop but plan on going to a 12X6 next time out. Using a smaller engine kept my weight down to 7.6 lbs. This is one great flyer that will scream at full throttle and slow to a crawl beautifully with no stalls. In my opinion a .75 is more that enough engine unless you want to do 3d. happy flying