Two questions. 1. I have 2 os 91 four strokes. Marvelous engines. I am putting one in a SIG King Cobra, and ground clearnce is a problem. I presently run a APC 14-7 at about 9400 on 15%. Would a APC 12-12 size give me about the same performance? Or would a 3 bladed prop be the answer? Twelve inches is about the max clearance I have. What is the difference between a OS 32SX, and a OS32SX-H? I know the last one is a helo engine. Is there any problems using the helo engine in a sport plane? I can get a good deal from my LHS. Thanks for your help in this matter.