Hmm you won't like my answer lol Cuz I don't believe any of those products work.
I think the best things you can do to improve your hair growth are:
1) Stop using harsh shampoos (specifically, avoid sodium lauryl sulfate "SLS"), these dry out your hair.
2) Stop using heat styling or dyes, these cause irreversible damage to your hair.
3) Use a wide-tooth comb
4) Eat a well-balanced diet and take multivitamins.
5) There are mixed opinions on -cones (silicone, dimethicone, trimethicone). Personally I avoid them because they cause build-up over time which can only be gotten rid of by the same harsh shampoos that I avoid. It causes a vicious cycle of hair damage imho.
Mmm there are lots of other little things, but those are the most important. Basically, the best way to speed your hair growth is to take better care of your hair. The more you damage your hair, the more frequently you'll have to trim.
I would recommend going to http://forums.longhaircommunity.com/sho … php?t=7804 and reading up on this forum. Lots of great advice. I'd never have gotten to waist-length without them, though I'll be cutting it back to bra-strap length in the near future as that was my personal sweet-spot in terms of looks and manageability.