Hi, I stumbled upon some motor mount inserts for the ST, and ended up looking to see what the differences were between the two mounts. They seem similar enough for something like a motor mount insert to fit for the regular motor mount. I would just get a full-on aftermarket motor mount, but it rattles the car a little too much for my liking. Here's the link for the inserts in case anyone else wants to take a look to try as well?
This Focus Mk3 ST/RS Front Upper Right Engine Mount Insert by Powerflex is a polyurethane replacement bushing that includes a lifetime warranty.