BMW PE update:
The BMW PE exhaust has really come through. A couple of months later and a couple thousand miles made a great deal of difference in how it sounds. It sounds much more aggressive, has a nice throaty tone and true growl once you push the car past 4,000 RMP. Only now have I been as happy as I am with this purchase.
If anyone is/was/has been on the fence about a PE, I would say go for it. It's great!