Well i got the idea off of here.I filled my arrow with silicone:
Here is the skinny[:'(]

Before silicone
28/12 inch 45/60 Carbon Tech Witetail Xp:
373 grains and 299 FPS.
74 pounds kenetic energy

After silicone
880 grains and 125 FPS
30 pounds kenetic energy

The silicone added 530 grains of weight and cost me 176 FPS.I did not shoot this through a chrono to verify,but if Bowtech is accurate with their statement that every 3 grains added will cost 1 FPS then i guess it's close.The reason i did this was to see if adding the silicone.Well i will put it this way i shot two normalidentical arrows through paperat 10 feet and got bullet holes,then i shot the heavy arrow and much to my surprise i got a 3 inch tail left paper tear,so i shot it again and sme thing.I think i will stick with weight tubes.

By the way Trykonstein how do you like those FMJ's?