Think carefully before you go ahead and supercharge. There are a number of things to be taken into consideration. You can't just buy a supercharger, whether it is a turbo or an engine driven one, and simply bolt it on. The present compression ratio (CR) of your engine is too high for it, so you would need to lower the CR. This means changing the pistons.
Because you are supercharging, the combustion temps rise, so therefore you need pistons to be able to take the higher burning temps. You would also probably need to fit an external oil cooler and fit a larger radiator to take away the excess heat.
The G60 engine is a supercharged unit and it is almost entirely different to the normally aspirated engines that Golfs usually have. This because during development of the modification stages done by VW to make the engine supercharged, most things were modified or changed including the cam shaft, the head, the pistons, the injection system, etc..
Whilst it is possible to supercharge your engine, it would be better if you just bought a G60 and then service the supercharger. Cheaper anyway.
Look at the projects part of this forum and look up GTI Joe's project. He is turbo charging his engine, and the amount of work to be done is considerable.
