kenneyd

Goal. Increase volume without changing sound/tone or looks
Tools, Just an Ev12 socket(or 12pt), sawsaw and a welder
Time, 2-4 hours.
Cost: $18 for SS butt-end exhaust clamps

Outcome. Its hard to tell from the video, but there is a noticeable increase in sound. specifically on cold start up, low revs and WOT. Its not dramatic but that isn't necessarily a bad thing, this isn't an 3rd gen Camaro lol. To my personal taste, its about 50% of the volume increase I was looking for. I will likely address the resonator later. I think its unrealistic to get crazy sound without addressing the catted downpipes as well
One thing I came to the realization of is, compared to other exhaust (example, the w211 e55), there is very little attempt by MB to deaden or absorb sound in the factory system. SO pulling random numbers for illustration, a stock e55 exhaust only allows ~15% of the sound potential out, so gutting will provide a huge increase. In the contrast, the stock w212 e63 system already lets out ~80% of the available sound, so doing this mod gets you up to say... 90%.
The aftermarket alternative like EISENMANN, renntech, FI or capristo etc for $2500-$6500.
The other popular options are to delete the resonator or the mufflers, or both. These are very good options, but there are a few cons that made me pursue other options. Cosmetically, You're at the mercy of to exhaust shop for the quality. Many of these I've seen will just use mild steel with crappy non-mandrel bends and even wrong size pipe. You cannot really DIY either unless you have a pipe bender. So this muffler mod method looks stock, its quite un-intrusive, reversible if needed. It also wont throw any flags if you need to take it to the dealer if that's a factor to any of you.
Its very popular among other car circles, such as corvette, bmw, w211 e55 and even ferrari guys.

There is possible more potential if you have time to do some R&D. You could try closing off that first Y that just dumps into the cavity or weld a pipe that goes from it to one of the tips etc. I have a feeling it is related to sound quality, so for now I left it.
My future plan is to cut open the top of the resonator and do something similar to to. However, since clamps wont fit, I will just cut a 3" pipe in half and weld it to the outside of the internal perforated pipe and close it back up. Someday i may get downpipes and at that point I dont want it too-loud either. so I may not touch the resonator

Heres the vid

AKnight55

Nice video!

hardyli

Lol your video was recommended to me by YouTube tonight. Then I saw your post after watching the video. Nice video! I learned more on w212 exhaust today. But personally (purely my personal preference) I like the tone of pre-mod sounds better with that rumbling. But definitely I can hear the volume is up after the mod, which is what you wanted to achieve.

Mojo20032004

Nice Job editing and incorporating different vids into 1. I was able to tell a difference in sound. Wonder how your muffler mod with cat-less dp will sound now that the fiberglass is removed and essentially making it a almost true straight through design. Nice on Ken!