I thinks it looks as good as my OEM spoiler. It holds down with just the 4 bolts and the stripping on the underside doesn't adhere to the trunk. That makes it easy to install and line up perfectly but I wonder if any water can get under it. I'm assuming no unless someone is pressure washing it. It's really tight to the body so I'm not worried about it. I've tried to wiggle it and it doesn't move. I hope that helps.
2014 GT Premium, Sterling Grey, 6 Speed, 3:55 Gears, Comfort Group, GT500 AB, 3dCarbon Spoiler, JLT CC, Boss 302 Alcantara steering wheel, FRPP TrackCal, FRPP Brembos, FRPP Wheels