2003 MSport 540i showing exhaust mod on cold morning. Headers have gutted primary catalyst. Twin main catalyst still remain. Resonator has been deleted with 3" piping to the stock M Sport muffler that has been welded straight through (piping goes straight thru factory muffler leaving appearance of stock). Basically, this is what the M62tub44 sounds like with only main cats. Basically 3" single straight pipe from after cats back. Sounds amazing. Will post more vids of full load, in car, or revs if you want. Maybe a tunnel run if you're lucky!