I have only seen one TT .91 at the field and it was mounted at about 8 O'Clock in one model and completely inverted in its second model. It ran absolutely superbly in either position once the idle mixture was leaned to optimum.

This particular example was a very impressive runner indeed. If they were all like this one (they may or may not - I just haven't seen enough of them to verify), I would recommend the TT .91 in an instant.