Local Combat Ace, Jeffery Rein, has been campaigning an ARF Smoothie in OTS, Classic, Intermediate and now Advanced. It's powered by one of his old Magnum XL .36 (round cylinder) SLC engines, same venturi, same compression, different glowplug, different prop. We got him to open the venturi up from .250" to .265", and change from an 11-4 APC to a 10.5 x 4.5 APC fairly recently, so lookout! Stock muffler, OBTW, + metal uniflow tank.
Regarding the venturi size...it was either that, or shorter lines, as it sagged a bit overhead. A filter or layers of pantyhose will return the effective venturi size, if this is too large. It's looking better, tho the covering is starting to slide off onto the pasture like a hot cow pie. The Smoothie is a good flying model, if you get it all tweeked up right!
Steve