OEM Exhaust Back boxes size

[gallaghb]

Open the silencers on the upper surface and remove the pipework and reconfigure. The objective is to remove any "reverse flow" which allows the exhaust gases to exit the system faster because there's less resistance to flow. The photos below are what I've done to the silencers on my Z4MC.

Do you literally have to cut open the silencers though? And then presumably weld back together?

 

[exdos]

Do you literally have to cut open the silencers though? And then presumably weld back together?

Unless you can devise a way you can gut them like you would a chicken, through the tailpipes, then you have to cut a window as in my photo. :wink:

The best thing to use to cut the window is a 4.5" "ultra-thin" cutting disc with an angle grinder: it removes very little metal for the cut, so that when you reweld the casing, you have almost metal to metal contact at the join.

You should work on the upper surface so that the weld can't be seen when the silencers are back on the car. I use a plasma cutter for removing the internal pipework.