I found some of those truck lug covers at various sizes at a local truck stop. Cheap,, chrome,, does the job well. Those bolts you show I don't have a problem with since I have the Vic Performance pipes and they are covered by the pipes, but the bolts on the flanges I used the lug covers and a dab of silicon adhesive. Also got a couple of larger ones for the rear tire axle cover. at about 50 or 60 cents a piece you can't lose. Visit a truckstop, haha.