I'm wondering, because I had a British bomber attack Wilhemshafen, itself defended by level-9 AA (and 110% effectiveness), and never saw the small black exploding puffs indicating AA hits. Thus far, after seeing enemy planes fly over a few of my AA-defended provinces, I've yet to see any of the black puffs I'd grown accustomed to in Vanilla. It seems the only thing my AA defenses do is encourage the AI to avoid/bypass the strongly-defended provinces. I was expecting a level-9 110% AA to blow a lone bomber out of the sky if it was silly enough to sit there for 4-5 hours bombing me while the AA is shooting at it the entire time. OTOH, enemy AA seems to work just fine when *I'm* the one in the crosshairs.