If your dealer told you not to adjust the shocks you should look for a new dealer. The manual gives the settings for different rider loads. When two up I have them all set up to max. This greatly reduces the tilt going into corners. When riding two up my GS is loaded to 350 lbs and never has bottomed out.Yes they are adjustable, but our rep told us that you're not supposed to or it will upset the handling characteristics. Its also very hard to adjust the rear...theres no room for a spanner in there. Although, it definitely needs more preload on the rear and better damping all around. Are there going to be facotry performance shocks? Maybe some nice HPG ones?
I'd like to give a Spyder to the guys at Ohlins in Sweden and see what kind of sweet bits they come up with