They are nearly the exact same engine excluding the exhaust. The round exhaust will give you a little freer top end, the Wasp has a slightly larger cooling head which is not needed as these engines run best right around 190-200 anyway. I had two of the older Trinity/Picco's one standard exhaust and one round. The round did pull harder on the top end but that was all. I currently have an Orion Wasp .12 rear exhaust, tons more power but it's kind of tricky putting it down on a slick track. Larger outdoor tracks where you can really get on are ideal for this engine. It's a real bulldog. I love Picco motors!