Well, from what I'm told there will be a better spec'd 320D some time next year. Thing is I didn't want to wait until then. So what I'm thinking is, once a few months pass, maybe try and get my hands on a nice AC Schnitzer or Hartge exhaust system to make the exhaust a little more lively!
You could always opt for the sport muffler if all you're after is a nicer sound without any gain in performance.
As for it raining BMWs, yes they are going to take a fair slice of the pie at least until the new C class arrives and also until MBIL start offering better equipped Es as well.