I think your going to get people on both sides of the fence here. I personaly do not use soft mounts on gas engines, I own several and have not had a problem. If you look at the paperwork that comes with a Bisson muffler it say's the warranty is void if you use a soft mount. Johng, what you are experiancing with the stinger is nothing out of the ordinary, they have that problem even with soft mounts, I think its because the airframe is not as rigid as most. Rubber grommets stuck through the firewall don't seem to do much and they don't last very long, lord style mounts allow way too much movement, even the large 1.5" ones. I am however sure there is a system out there that will work, but I've never found it.