What car are you driving? seems like the bottom is pretty nice, tire dams are a nice feature, but i find it's best to keep them modest to big will quickly add drag. a grillblock will work wonders, although it can take some experimenting to get it right,
my advice is to keep things simple and black, that way it's easy to change things and black stuff on the bottom of the car will be barely visible, so you don't have to spend a lot of time to make things look perfect. (also a little mud spatter on the mods will blend tem right in with the rest of the car
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