engine braces???

[chigger]

Hot VWs and VW trends have both had articles on converting a swing axle pan to IRS. They should be available as reprints. I would try emailing them as they are good to answer questions.
If I remember correctly the wishbone has to be flattened in certain areas around the axle flanges and two mounts for the trailing arms welded on. I would go ahead and get the articles first to see if you want to tackle the conversion as it is quite involved. An IRS pan is bolt on except for two mounts in the rear which have to be built up or cut down I don't remember which.
The weight is not so much the problem with the T4 motor as much as the torque is. Since it requires a rear mount to put it in the car, the mount can control the torque quite well. The long term problem is that the rear mount which is usually mounted to the bumper brackets on the body or some where in that area, will cause fatique cracks after a while. Reinforcements in this area are recommended.
The kafer cup brace is for strengening the wishbones which the engine and trans mount to. With high performance engines the wishbones will flex up and down as the power loads and unloads causing wheel hop. Wheel hop is a major cause of trans failure. I made my own and they really make a difference in the strength of the rear suspension and wishbones. Before you could wack the wishbone with a hammer and watch it vibrate afterwards I could jack it up under one wishbone and the whole car would come up without flex. All three pieces are required to work properly. This is one of those mod which is light and easy to install and really helps alot. Hope this helps.