I have the M Perf. Exhaust on my E90 and am in the WPB/Boca area, if you're interested in hearing the exhaust. The only caveat is that I'd have to wait until early Sept. because I have family visiting through the end of Aug.
IMO, the car should have come with the exuahust from the factory. I've owned a C63, which I believe had the best factory exhaust system out there. The M Perf. makes the M3 very comparable in terms of sound volume and aural excitement - it completes the M3 package. It is costly but it will bolt up perfectly in less than one hour.