From what I have read, oxegen combined with propane through a conventional dual pressure acytelene torch is low efficiency (in terms of the O2 consumption) but if you get setup with an injector style torch which uses venturi vacuum to "pull up" the propane and mixes it better with the O2, then the efficiency is much better. THe only injector torches I see available are fairly heavy-duty welding & cutting torches, anyone know of a lighter duty injector torch more suitable for framebuilding brazing?