To improve your suspension I think that you will need to do a few things. The front end can be much improve by changing the springs. I would say that non progressive springs are better but that is a question of taste. Race tech make very decent springs. I would suggest this as a first operation before changing the valves. The second step will be to adjust the springs with the proper size of spacers. Once that is done and you still fell that it is not right you can consider the valves. On my XX I did change the springs and fooled around with spacers and oil for a while and I finally have quite right without changing the valves.
Once the front is done you will notice more how poor the suspension is in the back. The problem with most bike is that the back suspension is more a spring than a shock. Even at soft the back of the XX is bouncing all over the place. To really cure that you do not have much choices. You will need to replace the shock. You will notice that in most cases, you get less spring and much more absortion. Really the idea of the suspension is to keep the bike on the road. Different options are available from either Ohlins, Penske WP, Bituto, Technoflex and on and on. I did put in a Gubellini, made in Italy by FG Special parts, similar quality as Ohlins but a little cheaper since the preload is adjusted wuth rings rather than a know. I must say that for 200 Euros, I did not care much about the know.
How much will you spend depends on how far you want to go.
Springs, more or less 100 $
Shock, from 600 to 1200 $
Valves, I have no idea or you can get crazy and get Ohlins fork, 2000 to 7000 $
http://bitubo.com/
http://www.fournales.fr/
http://www.technoflex.nl/
http://www.wpsuspension.com/
Hope this help.
TBS
