The saito 100 works just fine inverted and using only an elbow style header(like the earlier 91 models) without muffler. This will give your Spitfire a cleaner appearance. Just make sure you still run a vent to your fuel tank. Like others noted, with a Saito 91, mine required a lot of nose weight to balance. Also, I landed mine with half flap. The plane was more difficult to land with full flap. I never tried landing it without flaps, but from the sounds of others on RCU, it might be better.