I built two, one with a 26cc gas, the other with the Saito 180. Neither one is too much for the plane, both sure sound great, and of course, lots of power. Glassed both with 2.5oz glass. Which ever way you go, you'll love it. I found it to be a great kit to build, just as the 51 is, the 85 incher. Is that a word, "incher"? Have fun!