I worked at a Pontiac dealership when I was in college, and can tell you that every kid who stuck decals on the back of new cars stuck 'em in a different place... usually the left hand side, sometimes on the decklid, sometimes on the bumper, sometimes in the middle, sometimes on the right. (They were always crooked too.

) I'd say you could put it wherever it looks the best to you, and call it done. I thought I was the only one that freaked out about stuff like that.