My very first brew a month or two ago was a Citra pale ale. It was very good but it only yielded about two gallons and it's long gone. I'd like to do it again but maybe try to improve it in a couple of areas. The hoppyness was just perfect, Magnum for bittering and Citra for flavor and dry hoping. I used American 2 row (90%) and crystal 40 (10%). I'd like to add a little head retention and maybe a little thicker mouth feel. I'd like to keep the abv at the same level, near 5.5 or 6%. What would be some possible adds to the grain bill for head retention and mouth feel?