I finally got to see it at Aerotop at Poitiers yesterday. The commentator said the the engines are 200 hp Continentals and the engine choice/installation was, in part, to give a sound as close to that of two Merlins as they could achieve. It may not have been the real thing; and is only three quarter scale; and doesn’t have Merlins – but none of those things detracted one iota from my enjoyment of watching its performance!