I flew mine with a Brison 3.2. 52cc gasser. If I was to do it over again I would use a big Moki or Saito. The gassers are too heavy and the firewall to fuselage structure does not handle the combustion impulses well. They will separate over time. The 33% GP Pitts and the 1/3 Byron are for all intents and purposes the same plane. The Byron weighed more though.