Dinan, I have the new subwoofer kit from Bavarian Motorwerks and I'm very happy with it. I've had it for about 4 weeks. Like you, I had the standard sound system (no DSP) and the subwoofer has made a dramatic difference in the bass. The level of bass is just right -- rich, deep sound, but it isn't booming or overwhelming.

Also, the fit and finish of the sub enclosure is first-rate. Overall, I'm a very happy customer.