RE: weight tubes in carbon arrows
Matt/PA showed me a great setup for changing wieght and spine from Gold Tip.
You can get wieghts for front and back. So if you want to add wieght only, add equal front and back weight, if you want to change spine, take away or add weight to front or back.
Go to gold tip and see thier setup.
I was going to look at wieght tubes, but they are expensive.