for whoever has a ZEN 50 with a two stroke how did you mount your engine sideways inverted or upright and with what muffler

On the first one I had (the one that the USPS stomped on ) it had a Rossi .61, side mounted with a tuned pipe mounted under the provided belly pan.

Mine has a 4 stroke; there is however this other person at my club who has mounted a 2C 61 inverted; I see him starting the plane inverted all the time, don't know why, all my 4 strokes are inverted yet I start them with the plane the right way up (engines inverted).

He's probaby trying to keep the engine from flooding when he primes and starts it.

I've seen a ZEN 50 with a 4-stroke mounted inverted but he couldn't get it to start. I think he had a bad plug though.