Tam advised me on the P120 and the P160 that the end of the exhaust nozzle of the engine should be exactly 5/8" ahead of the bell mouth on his pipe. There should be a clear area measuring exactly 5/8" between the end of the engine nozzle and the beginning of the pipe. That produces the highest thrust on each engine. Probably wouldn't hurt to verify it with Tam, but that's what he told me recently.

Works for me!

Regards, Les