Capt Todd, Yes, the Dle 20 is a perfect engine for the Waco arf unless you want to hover. Mine flys awesome with large loops, barrel rolls, etc. Not under powered at all. Plus it is a very good fit inside the cowl. JTEC muffler originally designed by JTEC for the Arowworks Cessna 195 Dle 30 engine. I called JTEC and he made some for the Dle 20 which fit perfectly in the Waco with 2 down pipes exiting the correct place.
www.jtecrc.com