I'm sure you're gonna get a lot of opinions on this one. I run a ZDZ-80 single on a Carden CAP-232 with a KS cannister. With a tunnel built into the fuselage, we had to use the shortest coupler possible so that the exit hole is in front of the wing tube. We wenen't sure how it would work with a header that short. My engine develops tremdous power (7,200 rpm plus) with a mejzlik 26/10 prop. All I can say is that my engine doesn't seem to care.