I already have the rear exhaust boxes removed for the m3 style exhaust so just have straight pipes on the back half. Not that loud really and certainly can't hear the turbos.
Will try the filter and heatshield when weather gets a bit warmer.
Some Diveter valves give of a little whoosh and whistle without the big pish bangs!!? Are these even available or fitted to a 335d??
So, guess thats it then, no other ideas chaps???