Another thing I've tried is just combing it in all directions deep by the roots (like, straight from ear to poll, and flip it over to the other side and comb it, then back to the normal side again, etc). You can also get your hands in there and just massage away for a bit. My horse really enjoyed this massaging. Anyways, my point here: all this will get out those tiny down-like hairs (possibly some others too) and really lessen the bulk of the mane. Pulling would be ideal, but in a short amount of time, this method helps partially. Again, after a workout would be best and not slippery conditioned either.