The general opinion seems to be that this part is not needed, I have asked the company who made the C3 one for a quote on a strap of the correct length so I await their reply and will make a decision then. The backbox is in remarkably good condition and if it's not the original I think it must be OE as it still has a fully functioning exhaust bypass valve ! I'm going to refit the backbox for now the new shiny SS will have to wait till next year.