Welcome to the site.
Your weight is about what the bike is set-up fora s delivered but if it fels to stiff for you I'd read..thoroughly...the excellent section in your owners manual on suspension set-uup, it is very well done and will tell you what to do with your adjustments to make the bike feel like you want it to feel.
If that doesn't do it your manual gives you the size of springs that you can buy and install that will work with your stock valving both softer and stiffer, look that up and if you can't do it with the adjustments then try the optional softer springs. After that all that's left is the re-valve, but at 160 I'd sure try the adjustments followed by the springs first.
Buy this as soon as possible and follow the directions in their entirety :
http://www.crfsonly.com/catalog/product ... ts_id/1096
Once you try it you'll kick yourself for every ride you didn't have it done
!
This'll make your life easier too :
http://www.crfsonly.com/catalog/product ... ts_id/1333
Doug