Great choice on the Aero Kit, it will look
I had a full kit put on my car the other day by Woodman MINI

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On the subject of exhausts, because the diesel's points downward, the dealer was unable to fit a chrome tail pipe to the standard back box... So as a result I was also looking for a soloution, so that I could fill the 'hole' cut out for the exhuast.
Anyway, after looking around Im having a custom back box complete with tail finisher made by PowerFlow exhuasts for £170. They have agents all over, so take a look at their website and find a place local to you to get a quote..
Hope this helps a little? Any local exhuast specialist should be able to sort you out though.
Regards,
James.