Just ordered an M5 Lemans Blue/Caramel. I ordered the upgraded sound system. I'm wondering if anyone can tell me if it is worth the extra $$$. I have a 91M5 now and pretty much enjoy everything about it. Sound is pretty good to.. Can't really find any specs on the upgraded sound option. I know the M3 is a Harmon Kardon unit. From what I can tell the only differance is the bigger woofers...is it worth it??