BMW E30 exhaust and silencer replacement
Is replacing only the rear silencer enough on an E30 exhaust?
It is enough if the rest of the exhaust is in good condition. So first check the middle section and the mounts. The durability of aftermarket exhausts varies by manufacturer: with some, the centre silencer has failed within a few years and caused loud noise at road speeds.
How are the mounts for an aftermarket exhaust made?
An aftermarket exhaust does not necessarily have mounts. The rear silencer is fastened to the hanger hook with two clamps and a hose clamp, and the pipe to the original mounting bracket with clamps. You can make the mounts yourself from flat bar, weld the hooks and drill the holes: the result is sturdier than ready-made ones.
Where can I get the E30 front downpipe and front pipe, and what is the pipe size?
Not every manufacturer has the front pipe available: for example, the front downpipe of a 325i has had to be ordered separately through a parts dealer. The original pipe size of the 325i is two pipes of 45 mm outer diameter. On the six-cylinder, cylinders 1-3 and 4-6 run in their own pipes.