I've got a 99 540i 6 speed. I cut the muffler off and added a piece of tail pipe to route it as stock. Very nice mellow gowl until about 3k then sounds as a European V-8 should. The bonus is a much stronger top end. Do not remove the resonator as it will be much louder and pop and backfire when decelerating. Total job cost was 70 USD for a muffler shop to add the tail piece.