Not me!!, the only thing going ballistic is the tipo!! I'm sure one could be converted to 4-cycle. They're fiberglass, so if you were starting from an old kit you'd probably have to mount the firewall a little aft of indicated. It would be very similiar to the SPA guys flying the curare. They use the same wing cores I do know that. The tipo is a modified Curare basically. Dick Hanson made a few changes here and there. Our Tipos have the old style strip ailerons, so at slower speed the roll become really mushy, but I'm sure a set of barndoors more like the modern pattern planes would solve that. The airfoil is fairly thin, but the design overall is very clean. I've been practicing SPA Expert with it for a few weeks, and the plane absolutely screams on the downlines....top hat, etc. We have a phoenix 8 as well, and it is much slower on the downlines than these. Overall though, at slower speeds, these do feel heavy in the air. I'm guessing since the Curares are wood fuses, you could lighten them up more than these and start to swing the wingloading in a more favorable direction for slower flight. It's not that I'm a speed junky, heck look at my avatar, that UCD certainly is no screamer, especially with a 15x4. My point with these planes and the pipes is that in era they were designed, pattern was flown a little hotter than earlier...or later for that matter. It's all fun, that's all that counts! I'm sure a muffler would work, just less power.