Yes, inject ............ its too large a hunk of meat to get flavor from just a rub or smoke . I do the Chris Lilly Champ injection from the Cooking Topics page at this site. Lilly has won first in pork shoulder at Memphis In May 10 times with this recipe.
Recently, I smoked four pork butts. On one of the butts I did the Chris Lilly Champ . On the other three I injected with Butcher BBQ pork injection, and used Butcher BBQ Honey Rub on one, Meat Church Honey Hog on another, and Meat Church Holy Gospel on the last one.
Mrs Dollar and I agreed that Chris Lilly was the best by a long shot.