Dru, the engine box is for two stroke engines; I'm using a 91 Surpass.

The problem was that with the Sig mounts on the thrust line, there wasn't enough "meat" left in the top of the firewall to hold the upoper blind nuts. The adjustable GP mount will allow moving the mount holes down enough so the blind nuts will be fully supported by the five-ply firewall.

Using an auxillary ply plate like you mentioned would either; 1) move the mount forward enough so that the thrust washer would stick out too far, necessitating modifying the cowl, or 2) placed on the back side, it would cut down on space for the fuel tank, which is already tight.

Thanks for the ideas, though. I have three very well-stocked hobby shops within a 60-mile radius of me, and not one of them has this mount. Gotta call The Empire this morning and order one...