All suspension components are the same. 100% swappable.Usually we only talk about sway bar swaps, but is the steel suspension different and swappable as well?
I would expect the springs to be pretty similar. Handling is adjusted by the shocks' dampening action and (as already mentioned) the anti-sway bars.
There are a number of European based Spring and/or damper (shockers) suppliers who make components specifically tailored to achieve what you are looking for. This is far simpler than trying to build something from another OEM's parts box. I suggest you have a look at the following brands......
These are but only a start, Europe has many suppliers who cater for "street" based Cayenne Suspension, and as such this includes the Touareg..
The only limit will be your bank balance!
I did hear, but don't know this for a fact, the T2 in the US did get a softer suspension as far as the non air setup. T1 was the exact opposite in that they seemed to have a stiffer suspension than what others got. My T2 has air and I have never driven a non air T2 to know the difference. I would think as others have said it should be a direct bolt up, just not sure if you will get what you are looking for by doing the switch. I have not read where anyone has done it.