The billet 2 pad calipers are at least as good if not better than the 4 pad calipers. Plus, they're about half the weight so reduce unsprung weight.
There are quite a few different options for going radial. If you have Ohlins R&Ts then you can replace the caliper mount which bolts onto the fork bottom with a radial mount version circa £700. If you have Showa forks then you can replace with PVM radial fork bottoms and both K-Tech and JHP do radial fork bottoms for Showa as well. All priced at around a grand!
However, your problems (financial!) have only just begun. All of the above conversions are designed to be used with race calipers (whether they be Brembo, AP, PVM etc). All the race calipers use 108mm mountings (i.e. 108mm between centres of caliper mounting bolts). The Brembo radial calipers on the 999R, Aprilia RSVR etc have 100mm mountings so they won't fit! Also, Brembo race radial calipers retail for around £1200 each!!!!
Your other option would be to speak to someone like Roy at Polygon Engineering who will make you (and fit) a pair of radial mount fork bottoms to fit any caliper/fork of your choice to whatever design you would like so you could have them made to look like the bottoms on the factory bikes. When I last spoke to him, he was quoting in the region of £400 per fork bottom. So for approx £1200 you could have the fork bottoms and the cheaper Brembo radial calipers. Having said that, if you already have Brembo 4 pads on there then you'll probably not notice much difference - look bl00dy good though!! Brembo race radial calipers on the other hand then yes you'll notice a HUGE difference! How deep are your pockets?
Hope this helps,
Neil
P.S. Brake lines shouldn't be any more expensive than for any other set-up.
[Edited on 30-1-2004 by neil748r]