After many years of pulling when I did H/J, I finally have one with a long mane......but I have also learned from one of the top reining barns, that if you actually trim the bottom with scissors **GASP** it makes it grow nice and thick, as well as neaten it up a bit. So, I trim it carefully, then just go down the mane with the scissor tips cutting very tiny criss-crosses in the ends to make it so it doesn't look just straight blunt cut. More natural. I am not good with the razor thingys smrobs referred to......same idea. But-I also bang his tail........its a reining thing, I guess, but sure seems thicker.