I have read through some of the prior posts, and my question remains???  What is the best way to add about 80 to 100 grains to my carbons?  I shoot a 60" longbow, 56#@28.  My current arrows are about 460 grains with 145gr points.

wieght tubes, or a heaver insert or both.

A tad more info will be necessary...most likely its been done...here are a few ways, but knowing the type of bow and what arrows you are talking about will be necessary...

Weight tubes, weed eater line, stiffer arrow/heavier insert and/or point, oatmeal, sand, other arrows inside, different arrow....you get the drift...

If the arrows are already shooting well for you, I would go with a weight tube.  3 gr. per inch = 80-100 grains.

You can change things up front, but that's likely to mean replacing all of your points.

Are 460 gr arrows enough for bear, deer, etc???
I use to shoot 125gr points but have been trying 145s.  It seems to work well but am worried a little about penetration.  Maybe I will add a bit up front for starters unless anyone has better thoughts.  I have heard heavier arrows are also quieter.

Those are definately on the light side. Its hard to say without knowing more, but the weight tubes will have the least effect on spine while adding weight.

For Carbons I like the 100 grain brass inserts.
They also help strengthin the tip area also....

I had good luck with polyfill (pillow stuffing) Its not messy, its cheap and available at any fabric store.  You can add just the right amounts to get all your arrows weighing exactly the same.