I have a 91 OS 2 stroke I just purchased and I have the identical one in a Carl Goldberg Super Chipmunk. There is a large selection of props listed starting from a 13/8 all the way up to a 17/6. I have been using a 13/8 with my chipmunk and plan to put the new engine on the Hobbico Sukhoi. I am really happy with the the power on my chipmunk, but it is a bit fast and could use a bit more vertical. The engine turns up about 11500 rpm. What are the pros and cons on diameter versis pitch? If I go to a wider prop, say a 14/8, the RPM's will drop I am sure but what kind of changes will I see with the way the plan flys? The manual recommends a 15/6 which will lug the engine down to the 9000 rpm range I think.

Best regards,
Randy