Tuning a 2 stroke tuned pipe also depends on what you want to use it for. Originally tuned pipes were used to extract maximum performance from an engine a a given rpm. When done properly, this give an engine that is very peaky, or, when it "comes on the pipe, there is a considerable burst of power. This is fine for pylon racers, or motocross bikes, but it doesn't really apply to pattern airplanes. A peaky motor is a very bad thing in pattern, where smooth flying is were the points are. Ed Hartley's web pages at http://www.rcpattern.com/2cycle.htm give the best setup info that I have found for a 2 stroke. I fly an O.S. 1.60 with an ES pipe and Ed's web page gave me the best info for setting up my airplane that I could find.