Now I'm very picky when it comes to giving cars visual downforce and am normally opposed to adding a larger spoiler to any car, but some cars would really just look a lot better with a bigger spoiler.

Case in point, the new 2014 Mazda3 Hatch:

Solid looking car, but the slope of the rear hatch leaves something to be desired IMHO. Slap a bigger spoiler on there like the Speed3 (well, maybe a bit smaller) and we're in business:

What else do you think needs a bigger spoiler?