I won't give up my 4 stroke for a two stroke unless the BPA gets more contests. It's a chore to squeeze a four stroke in a fiberglass fuse designed for a two stroke. How about some good wood kits of the Atlas or the like which can be widened during constuction to accomodate a larger engine. I'm in the process of widening and lengthening a Phantom 1 from plans at this time. I like the OS 91 very much for many reasons. I would go back to old style pattern in a second with retracts and a pipe if it were allowed.