RE: Carve 133 vs GO 165: HELP!
Good to see that you're looking to take your windsurfing a step further. If you're considering an upgrade to the GO 165, I would thoroughly recommend the Carve 133. At the level you are at and as you enjoy sailing with more and more power in the sail, the Carve will offer more excitment. It will compliment the GO 165 nicely as Roger mentioned.
The wind range is pretty much the same for both the Carve 133 and GO 129. The GO 129 mentions a 4.9 as the GO boards are also designed to work with small sails with progressing sailors who do not plane fully yet.