The only problem I had with my Hatori short pipe was the spring pipe mounts on
the rear of the pipe constantly breaking, and yes, there was adequate clearance
between the header and the pipe. Check out this web site about building a Twister
and there are a couple of pictures of a new mounting method for the short Hatori
pipe that looks like a better way of doing it to me.

http://perso.wanadoo.fr/cmdieppe/Actualites%202005.htm

tommy s