Ah, good luck welding titainium, I have worked in the bicycle industry for a long time, both as a racer and a builder. True titainium can only be welded in an enert(sp?) gas environment. Meaning that the room that the welding takes place in is filled with Argonne gas, and then the welding can take place. There are few facilities in the U.S. let alone the world that can weld titainium. One of them is litespeed, and Douglas as in MacDonald Douglas the aircraft manufacturer. I would highly recommend getting a Stainless steel exaust so that you do not waste time and resources.