when i worked restoring Ferarri's/jag/porsches we used to hand make the exhausts/headers using the "Sand Method"
Basiclly you need to do is hammer a piece of 2x2 into the end of the length of pipe/tubing then poor in sand from the other end making sure its well packed in then hammer in another piece of 2x2 into the other end sealing the pipe/tubing
now you need a very very strong heat sourse - then apply to the area needing to be bent and get it REALLY HOT then start to bend it whilst still applying heat - Patients is the key, do it slowly