Byron T-33 Fan conversion Help needed
The O.S. .91 works extremely well with the BVM pipe on either a Dynamax or a Ramtec fan. I believe in most of the Byron jets the engine is mounted inverted. A flying buddy of mine has a Byron F-18 with the O.S. .91 inverted and has no trouble at all. He is using the stock Byron fan setup.
As you may already know, Trim Acft also makes tailpipes/thrust tubes which fit their Ramtec fan quite well. I would recommend that you use it for best results.