Jay
I personally think solid mounts are a bad idea.
As a better alternative, I have installed on my SPF and many others, Energy Suspension's poly mounts. The poly mounts provide a very rigid mount yet provide enough coushion to eliminate engine noise.
I don't know how these mounts could adapt to a Back Draft, but I'm sure it is possible.. If you want to discuss further, please send me a PM at
craigayl@comcast.com
Criag