If DPs+berk mids+Eisenmann race isn't loud enough for you...man you must really want it LOUD. Berk race is a muffler delete so it will certainly be louder, but it will also drone more. The resonated mids handle rasp very well, but the drone could be pretty intense esp. if you're 6AT. Berk is a good company though (see my mods), many people here run Berk race and seem very happy with it. You could sell the Eisenmann and have a good margin for a diffuser after getting the Berk setup.
E88 FBO N54 Alpinweiss/Coral Red/Meisterschaft Race/Berk Resonated/Macht Schnell 3"/ER CP/Synapse/VRSF FMIC/FFTEC LPFP/HFS-4 DO Stainless Lines/BMS DCI/BMS Thermostat Delete/Rob Beck PCV Valve + Cap/BMS OCC/PTF E50/ST Coilovers/M3 Front Control Arms + Tension Rods/M3 Subframe Bushings/M3 FSB/DINAN Camber Plates/Apex ARC-8/Project Kics/Macht Schnell Studs/VAC Hubs/Rogue Transmission Mounts/Alpina TCU Flash/Icarbon/Kerscher/BMW Performance