The .455 PTS. I disagree about the 3 bladed prop being horrible. It is pretty good for a beginner and has great braking action. Use it to learn, then toss it and the counterweight. You have a high revving, super reliable engine then at a great price. One piece, machined crankshaft. Hard chrome liners. Excellent carbs. Tremendous power. I don't like the Hangar 9 mounts that came on the XE2.