Suspension swap for towing

2006 mk5 TDI brm 1.9

Remember reading about swapping springs and struts from a Jetta wagon or sportwagon for a stiffer suspension. I believe as early as an 04 will swap?

Any info on year, part number, and color of the dots on the springs will help. I believe there were two or three different for colors for different spring rates. Any info on color or spring rate/weight would be great.

For reference I'm looking to tow an enclosed trailer 5x8 roughly with as much as two motorcycles. Not sure on trailer weight but bikes combined would be no more than 1000lbs

http://forums.tdiclub.com/showthread.php?t=395474&highlight=lift+springs . Still working well. I eventually added front spacers from uk and that lifted the front. Ride's still good, and the car's much better in snow. No squat with 100 lb trailer tongue weight.
I tow an 1800 lb trailer on long trips. 1000 is no sweat.
Data on the spring distance kit in this thread http://forums.tdiclub.com/showthread.php?t=425007&highlight=front+spacer .
I'm still using original shocks.