E34 Silencer box

[huattie]

It's time to fix the strong "purr-ing" sound originated from the silencer box (exhaust). Had this since I got the car almost 2 years back but did not do anything about it. I suspect the elements inside the silencer box is damaged or something.Any recommendations/views on fixing this problem?

 

[moots]

Mine's an m20b25 rear exhust box and I have had it "rebuilt" by JFA in Sunway.The innards looks like so:

So they cut it open,replaced the corroded and holed pipes,wrap fiber over it and welded it close.I requested Jaafar for as original a set up he can make(you have a choice).The outcome was not too good.The noise was better than before.After 1 month,till now,the noise became louder at idle but not noticeable at speed.