Hell yeah dude...put 'em on! Not only does it protect the paint and keep the car a little cleaner, but I think it adds more of a rally look.
Btw, many people say you need to remove your wheels for this install. Idk about the GR's (because I have a GD) but it's not necessary, easier yes, but not necessary. Make sure you have some offset screwdrivers or you probably will need to remove the wheels. Also, a pocket full of zip ties always helps. I'm the type that is paranoid about screws coming loose, so I often hide a zip tie in there somewhere to prevent losing the whole flap, should the screws come loose.