The DeCarbon shocks and stiffer springs are unique to the Willy and are highly regarded as standard.
If you just want to tighten things up a bit then you could replace the track rod ends, bushes and anti-roll bar mounts with either new ones or uprated ones (the rubbers will have deteriorated even with your mere 20k on the clock).
This is the route to take if you just want the standard factory feel. Fresh tyres make a big difference too, although BenR tells me that some of the more aggressive modern tyre designs arent best suited to the Willy. You might also want to keep your Willy standard-looking as its No.0002!
But if you want to lower it then the front will require a minimum of lowering springs (Id recommned new strut top mounts too). Im sure you know that youll need to have the torsion beam adjusted at the rear - and the brake bias valve tweaked, or youre back brakes will lock up all the time. The next step would be some quality coilovers (Avo etc). It would also be possible to fit some coilovers and not lower the car, although there might not be much point.