Don't know about bespoke systems but Harmon Kardon is my favorite from the factory - the one in my Mercedes big SUV is the best car audio I have had (including a bespoke Clarion setup). Mark Levinson factory installs in Lexus would be a close second.
A Porsche is pretty noisy in the cabin so I am not really sure of the benefit.
A Porsche is pretty noisy in the cabin so I am not really sure of the benefit.