Have you tries using Polybush Kits? we have just modified the rear training arm bushes for the escort mk3-4 on our budget range to allow adjustment to the stiffness and movement allowed. This is simply done by reducing the size of the insert and using a larger diameter bush either side. Simple mod with great results.

The polybush kits however are more expensive but can be made to your specification. Feel free to give us a shout if you need any more info.