Hi,
I thought PorKens RMB-"factory style" modified rear S4-silencer was a brilliant idea and are doing some more "research" before i go the whole way as PorKen did
I have not heard an RMB live, just on videos, and some of them has got a bit "old tractor-sound" at idle....pod-pod-pod-pod...
So as an experiment i am planning to keep the first/smallest section of the muffler, though gutted for its insulation. This to determine if the exhaust-pulses are going to be less distinct in its "pod-pod-pod" -sound.



These mufflers are hands down the best quality build i have ever seen, with an inner liner in thin stainless-steel and another thicker outer body stainless steel. No wonder its so heavy - and very quiet.
It some sort of "steel-wool" about 5 mm thick wrapped around the inner straight through-tubes shielding the small holes in them.
Rest of the muffler is stuffed with some sort of "rock-wool"
A very dirty job gutting it. I felt itchy on my face the whole evening after even after a shower. Some sort of mask to breath through and even a face-shield is recommended.

 

Interesting.

How does an RMD differ from an RMB?

 

Perhaps the D refers to deleting part of the internals? A new acronym!

 

Magnus!
Very interesting!!
Can you post a sound video when are you finish?
____________
Jimmy
89s4 Black black

 

He-he,.. well, the the RMB-acronym (Rear Muffler Bypass) is in a way "misleading" as it is more of an RMD (Rear Muffler Delete) when the complete muffler is replaced with some piping...at least in my head.
I have seen both used but I think RMB is more common. Maybe this can be called an RMG (Rear Muffler Gutting) as that is, at least partly done here.

But who cares as long as we all understand what we are talking about :-)

Can`t wait to get it all welded up and installed and hopefullly get a bit real V-8 rumble.
But the sophisticated exhaust note when standing outside and its beeing floored driving by as original is also quite cool, a muted low howl-raspy like sound....difficult to describe..just too bad one can hear very little of that when driving it.

dimi5928 !
Yes i will post soundclips, hopefully good sounding ones and report the results regarding any drone if present :-)

 

Sensible.

"Bypass" implies the muffler is left there and just bypassed, which is flat out wrong for the aftermarket ones For them, RMD.

Ironically, in Magnus' case, if he's just replacing the perforated holes with straight stainless pipe and sealing up the box again, then its probably actually an RMB

 

Hilton !
Just partly, as I am leaving the perforated in the smallest Chamber, though without any "Rockwool" to mute it. I hope that leaving this Chamber will "flatten" the tone a bit.

 

I have now driven the car for months with the above configuration. A bit disappointing i`d say :-/
Not very much louder than stock - just a bit more is heard inside - but "better" than OE.
A bit of drone inside between 1250-1750, loudest when decelerating. The drone is not annoying, but it`s not the sound you want.
The other night i went with the solution that PorKen did. I am very pleased, and for me this is the sound i am after.

- A bit louder. If you don`t step hard on it you will not wake up any neigbours. Not at all !
- More "raw" at idle. Not any of the "tractor-like" -pod-pod-pod-pod- sound but a louder deep sound opposed to the original weak "sigh" at idle
- I think the fact that the tubing merges into a common outlet maybe is the reason for that the original sound is kept but coming through deep and clear. At least to me i prefer this sound over the "two outlet" solution.
- Accellerate and that nice V-8 sound is - for the first time - coming through. But not "the full Monty" V-8 roar as from an Chevy truck V-8, but fairly deep and heavy and with a touch of "rasp" to it...
- I can now "hear" what the engine is doing in a clearer way - as the exhaust copies it into sound. I can hear the exhaust note back there the whole time, but i do not find i tiresome as i love this kind of "music"
The "deep note" naturally becomes very faint when the engine is working very light - but when any amount of load is applied with a little squeeze on the pedal you can hear it by the deep and "muscular" note again. But no droning anymore.

Bear in mind that i`ve got an -87 with the big mid-mufflers. If it does not drone i believe this solution also could be used with the small mid-mufflers even if i believe this set-up will be a little bit louder -- and maybe even more pleasing. I hav not heard it so i can`t tell.
No soundclips yet but i will post some later.

At least to those who`s got a car with the big mid-mufflers -- just do it -- you`ll love it :-)