The 4.4i Sport has twin "Black Chrome" circular exhaust tips (or at least they do in the UK) which I understood were an interference fit ( ie not welded on).
I think you can fit OEM chrome tips in their place. Have a look at part # 18 307 549 766 ( Black chrome are #18 107 500 498). Should be a straight swap but you'll need to eat some cans of spinach to get your "old" ones off. I am about to do this & will report back.