"How much up in spine wght? Move from 150's to 250's? "
Sorry, I'm not really up on the carbons. I've just started using them last year and the ones I have shoot great so I have not experimented with them. I've always shot wood in the past and the general rule was that if you went up 25 to 30 grains in point weight, you had to go up one spine group in stiffness which is 5 lbs. Carbons have a much broader spine range so depending where your current shafts fall, you MAY be okay. I'd try the heavier point weight with the shafts you have and see how they fly. If they impact differently, wobble in flight or just plain don't shoot, you will probably need the next stiffer shaft.
If your existing shafts don't like the extra point weight and seem weak, you can shorten the shaft a bit. Taking an inch off will stiffen it up quite a bit but you have to have room to do it.
How about some of you other guys who know carbons jumping in here eh?
p.s. If you do buy some new shafts, DO NOT sit down and cut them all to the same length as your old shafts. Leave them a good bit longer and start out tuning them that way. Add point weight if they act stiff and take it away OR shorten the shaft if they seem stiff. Bottom line, more point weight or shaft length equals weaker spine and less point weight or shaft length equals stiffer spine.