Out of all of the little non-used allen wrenches I have, I just picked one that was the right length and size, gave it a little 45 deg bend to clear the tank and mounted it up. It's been on the truck since day one and has not snapped off or bent a pipe mount. Nice spring steel that is flexible enough to allow some give without snapping.
I bought one of the GMK mounts but the wire was to thick and the thing was really stiff. I was more worried that the coil end wouldnt allow enough give and end up breaking something. Basically all it is, is a Dubro front wheel strut for a RC airplane, that has been bent to be used as a muffler hanger.
Spotted this awhie back, it acctually looks like it might work quite well, the wire is thin enough and there is more of a dampening action.
http://www.redrc.net/2007/10/orcan-exha ... nt-spring/