RM Motors End silencer BMW E30 318i 1.8 to weld

If you plan to modify your exhaust system to a greater extent, also increasing the diameter of the passage compared to the original, then we recommend ordering a model with an increased diameter of the passage

60 mm - model RM01/60/150/450
63 mm - model RM01/63/150/450
70 mm - model RM01/70/150/450
76 mm - model RM01/76/150/450

However, if you want a more subdued sound, you can order a version with a silencing embossing, available at another auction, the RM02/50/150/450 model. Or similarly for the version with an embossing, other flow diameters:
60 mm - model RM02/60/150/450
63 mm - model RM02/63/150/450
70 mm - model RM02/70/150/450
76 mm - model RM02/76/150/450

The through-tube diameter is always the same both inside and outside the muffler. We do not use the tricks of upsetting and expanding the muffler nozzles, where from one muffler model several models with different pipe diameters are made, and in fact the diameter of the passage remains the same.
In the case of universal use, the mounting side does not matter.