Check out Mike Focke's Boxster page about top/frame removal..
https://sites.google.com/site/mikefocke2/removingthetopandframe
1. top goes into service position.
2. For 97-99 Boxsters, remove carpet piece behind and to the left side of drivers seat to disconnect B-pillar microswitch (attached to the top's frame).
3. pop off the top pivot arms from the frame.
4. remove three bolts and two small phillips head screws from each side of frame.
5. To remove assembly, with one persion on each side of car, lift aft end of top.frame up and slide assembly aft the then lift out. Be careful not to puncture foam trays while removing assembly!
I've done this job six times and it is very easy and straight forward to do. I would estimate the weight saving to be more in the 50-60 pound range. You really need two people to lift it out once you've removed the bolts and screws due to the size of the assembly as opposed to the weight. I can easily pick up the whole assembly and carry it around once free of the car.
You do need two