RE: OS 48 4s question....
Thanks. The flex pipe option is too pricey for a non-cowled application. I have found photos of the OS .40 4s, and it has a header pipe that is flared on the cylinder head end with a locking nut through which the pipe passes. That would be ideal. The irony is that I once had a broken OS .40 parts engine that had that very same arrangement. Oh, well.
Thanks again!
Tony