I never would payed 4300 for this..I questioned my options at 3200..So I bought a 1 piece aluminum for 1300..I really don't like it ..Now back to a 2 piece..Mark Williams is the only one who has one and I never heard any complaints about them.. I haven't installed it yet to say how the quality is . My only complaint is that center carrier brace having paint come off an still being wet with all them wood chips embedded in it.. Will it hurt performance of it? Probably not .. Just cosmetic .. Does need paint to keep from rusting but at 3200 I shouldn't have to be sanding and painting.
Honestly, if it were me, it would be going right back to them for the repaint. Doesn't matter if it doesn't affect performance. It should come without any defects at that price tag... Do you need that specific DS, probably not, but if it makes the difference to you then it doesn't really matter if you need it or not.
Do you daily your cat? I drive mine pretty regularly and I have a 1-piece, but to me it didn't change much, really cheap insurance from my oem snapping and beating the hell out of the car lol
Contact them directly and express your issues with the damaged parts and depending on how they do business, they may try and compensate you with something in return...