We did a couple of subtle appearance modifications on the 335i this past summer. The first was a set of matte black kidney grills for the nose of the car. Although it would be easy enough to paint the existing grills, from experience we know that little rock chips will immediately peck holes in our black paint, revealing the chrome underneath. A better solution is to install grills that are black plastic all the way through. As it happens, we sell those, so we grabbed a set off the shelf and popped them on.
Install is extremely simple -- the grills just snap into place in the bumper. Pre-LCI (facelift) cars will have an additional "eyebrow" that attaches to the hood, but our 2009 car doesn't have that.
brake caliper paint kit, which includes a two-part epoxy paint that cures hard, glossy, and heat-resistant. Since we were already painting, we also painted the rotor hats. Our silver calipers and rotor centers look a lot better than the old rust color from before. If you don't like silver, the kit also comes in red, blue, black, yellow, and even orange.
The brake caliper paint kit comes with a handy can of non-chlorinated brake cleaner spray, which we used to soak down all the extremely dusty brake bits. As you can see, it's still a plenty messy job; gloves would be a good call.
Tech tip: Once you mix up the epoxy paint, use it right away, because it immediately starts to thicken, and in a few hours it'll be set up. We had one customer who didn't understand that and left it overnight... Also, hang the caliper from a coat hanger or bungie cord so it's not hanging from its brake line.
If you have the time and room, get the car off the ground on a lift or jack stands, paint all four corners, and leave it to cure overnight. By the next morning, everything will be nice and hard, and you can assemble it all back together without worrying about leaving thumb prints in your new paint.