(I posted this on TM and MINI2 earlier today and would like to share it locally, too....)
On Friday a channel swap loom arrived from Mike at NewMiniStuff. He had offered to modify it (at no extra cost!) to provide additional wiring and I bought a pair of OEM A-pillar tweeters at the same time (although Clarion A-pillar units are offered as a further upgrade.)
I started arond mid-day on Sat. Mike's full fitting instructions were very easy to follow, being aided by photos, and when I had a dashboard routing problem with the A-pillar units late on Sat afternoon he replied by email early Sat evening so that I was able to get it all working this afternoon (Sunday 13/12/09). His extra help + enthusiasm made it all possible and I thanked him earlier on "email@example.com"
It was hard work in the cold but I found the channel swap immediately gave Radio2 better bass and mid-range and that the tweeter upgrade was the 'icing on the cake' and produced the (very impressive) sound stage that Mike predicted. CD/mp3's will sound much better, too, I expect!
(I know it's not really a new topic but I think the NAM thread makes sense. I felt that a simple loom conversion would be 'less messy' and found Mike's address in Modern Mini. IMO the channel swap is an obvious upgrade and I'm convinced that the tweeters enrich it.)