I didnt realize that inverted engines were so finicky. I also have a Hanger 9 p40 Warhawk. It has a Evolution 61 with a bisson muffler. All of it is new. I cant keep in running. I thought at first my problems where because not only is the engine inverted, The muffler angles upwards before exhausting out of the two side pipes. Every time I think I've got it right, it dies. Ive had more dead stick landing with this plane than with all my others combined. Im using Wildcat 15%, I've used 10% and also FAI 0%. Just installed another number 8 os plug. At least the landing gear are holding up. Does anyone have any ideas or is this typical of inverted two strokes? Thanks.[:'(]