Hi all engine experts. I will begin work soon on an aerobat and would like to move from 2 strokes to 4 strokes. I am considering engines from the following brands: Saito, Magnum and OS. in the .91 to 1.20 range. Is there any problems that you have experienced when mounting/flying these engines inverted? problems specific to a brand or to a particular model? Due to price I am not considering the OS that has the pump

thanks in advance