The stock Z3 has black plastic mesh inserts in the gill cavities. I had been reading some articles on the bimmer.org message board about how easy it was to remove the gills and paint the mesh.
1 Several days later, I was wandering through Home Depot's paint department and ran across some chrome Rust-Oleum spray paint
3 The gills are held in place by a single philips head screw and 5 compression fasteners. Remove the screw and locate the 5 fasteners. Use long-nose pliers to gently squeeze the fasteners and push them out at the same time.
4 I didn't use any kind of gloss sealer as others have done. 10 minutes of work, 20 minutes of waiting for the paint to dry, and the results look great.