John_M_

Just for reference, here's images of the FT160 Keleo exhaust ( pitts style )... the header tubes are too restrictive ( long and narrow ID )... the expansion chamber is too small, not to mention the long exhaust exits.

So you make the headers pipe ID larger into a larger expansion chamber... the longer the run, the larger the ID should be on the header pipes, same with the exhaust exits... I've heard comments this pipe has about a 300 rpm loss on methanol / glow fuel, due to de-tuning to keep the engine temperature down... Mine prompts gas movement forward through the exhaust system, with no discernible loss.