Funny thing, this is the M5 of my Tuner near Nürnberg... amazing car, he's really convinced of his new M5 which was (in stock mode) way faster than his tuned F10 (720 HP)...
I had a Remus on my E92 and it wasn't made very well in terms of quality but offered awesome sound. With the new Remus parts it's vice versa...
Actually the sound is quite nice when mounted to a M2 or M5. I gave up regarding the M3/M4 and won't spend any money on a AM exhaust as none of the products is able to improve the poor sound of the S55.