It's not bad on my restored and modified daily driver '64 200, but it is noticeable at in-town street speeds. I've been told that brand Cs use some kind of counter balance weights in their convertible fenders to dampen movement, but that sounds like something that needs calculated engineering with extensive testing and doesn't sound feasible for retrofitting our convertibles. Despite all new seals and weather stripping, adding expensive sound deadening materials throughout and upgrading under-carpet padding, closing the doors makes the posts shake and the doors reverb until it sounds almost "tinny". I've seen braces to help control frame twisting for racing and handling, but I've never seen anything designed to stiffen or dampen vibration in other parts of the body to improve overall rigidity and reduce noise. Anyone else thought about doing this?