One Towne MINI mod to our new MINI was the JCW Sports Exhaust System ("cat back"). Ray K. has our OEM exhaust system tucked away in the Detail Shop temporarily.
OK, its not new, but our new MINI had 17 miles on it when we picked him up. That's less than the driving distance between Oxford and Towne at least.
I don't know the MINI hardware that well yet, but it should be a direct replacement for late-05s on up. It may need additional parts or modification for earlier MCSs.
I know a common MINI mod is a "cat back" exhaust system upgrade, so it may not be worth that much. I'm guessing $150. How about $100 for a MCOW member "cash and carry".