I've always thought of myself as a grower, as well. I go from around 5"-6" and 3"-4" around, when soft, to 9" long and nearly 7" around when hard. If the real average for cock size is 5"-6", though, maybe I am a little bit of a shower, as well.
From examining guys in the shower at school, I have seen some who hang as big as me soft, but don't get any bigger, when hard. I have never seen anyone in person with one bigger erect than mine. Man, the penis is a sweet thing...