Q1_Aircraft: Rotax 503 questions

Has anyone mounted the Rotax 503 upsidedown? I am toying with the idea
of doing it that way and also not using the fan that comes with the
engine. I can't see why there would not be enough air through a
properly fit plenum to cool the engine just like the continental is.
Also has anyone messed with any other exhaust system that would fit
better in the cowling? I know 2 strokes need their tuned exhaust but
don't see why it has to have the Rotax name on it or be the shape it
is. Maybe this is all just shooting myself in the foot but would like
anyone's suggestions that has been there done that.

Ron's Quickies
Q200 N4710P
Q1 Just Parts