I have no idea what I'm looking at
And you have company. I liked the way the stock system sounded on the 528e. My '88s had 44mm pipes exiting the cat, with a resonator ahead of the muffler.and out. Mellow and not fatiguing on highway. Guys, I'm looking at 6K$ worth of hearing aid so I can hear my grandsons speak. To many DBs for too long and the ears wear out.