A few years back Skyport was working on an STC to allow Alon style exhausts on all Ercoupes. We developed the heat muffs and stack drawings. The project was eventually shelved when the stack manufacturer threw in the towel. We found there were to many variations from one airframe to the next, possibly due to differences in the engine mount thrust angles, to allow a single stack configuration to work with all planes.
Also, my experience with repairing Alon stacks indicates that, even within the Alon family, there are significant variations form one airframe to the next. YMMV... -- John Cooper Skyport East www.skyportservices.net
