dustinN

Does anyone know the exhaust pipe size for our M157? I assume the W212 and W218 have the same exhaust system, right? The shop that did the resonator delete with straight pipes on mine the last time, the pipes are a bit smaller than the OEM exhaust pipes. I'm not sure but some said that might caused the vibration. I just wanted to make sure to have the right size this time. Thank you.

kenneyd

Looks like the outside circumference is 8 and 3/4.
I mean this roughly about two and three quarter inch pipes OD
I'm not sure exactly what a 3-in pipe inner diameter is, but if I did this, I would prefer to use a 3-in pipe to delete the resonator

dustinN

Thank you man. You are right, it's about 2.75'', I've just measured the diameter of the cut off resonator. Why would you prefer the 3'' one?

kenneyd

I'll have to double check, but I believe a 3-in pipe would fit nicely over a 2.75-in. would make a nice clean install.
​​​​​ it's really hard to weld two pipes of the same size together unless you have a pipe expander to flare open the ends

Magno

Exhaust pipe is actually tube, and tube is measured in OD (pipe is measured in ID).

Our cars use 2.75” OD tube (70mm)

2.75” is an uncommon size so most exhaust shops pick either 2.5” or 3” for a res delete. Sounds like your guy may have only had 2.5” stainless on hand so that’s what you got.

dustinN

Yes, I think I got the 2.5''. Where do you usually buy the 3'' tube? Thanks