I'm actually interested to see what they will do with the 4 banger c63's they will probably bore out the cylinders and do a bunch of other engine tuning so it won't sound like this at all.
The weird like zip tie ripping sound is part of the tune. I had a 2012 c300 with a stage 2 pop and bang and mine sounded somewhat like that when shifting because of the tune. It’s just backfire