Installed Direct Connection chin spoiler...flex???

Neither of those are affective for downforce. They look cool, and they do redirect a small amount of air into the radiator, but there's no real added downforce from them. Potentially just the opposite as the underhood area becomes a high pressure area. So they don't have to be very substantial. I have something similar on my LHS, and had similar ones on my E bodies, and my GM station wagon.