Thanks to you all who have responded! Your comments ARE helpful . I probably can't loose since both engines will power the plane fine. At this point I am leaning toward the OS .91 4-stroke because I think "Light is Right."

Next question? I have seen the engine mounted upright, inverted, and side mounted. Comments on the pros and cons on which way to mount the engine . Which works best AND preserved the beautiful looks of the Ultimate? Thanks for your input.

Redcatcher