The Begining

Eisenmann back box

I bought a Z3 exhaust on ebay last weekend, its in great condition just little dusty & some light surface rust. The o2 sensors were replaced with plugs (after cats). The new engine has all of the o2 sensors on the headers.

Below you can see the fitted exhaust. Unfortunately it’s a little short however all the angles fit perfectly; it will need lengthening a little. More on this once work begins. Seems as though the Z3 is a little shorter than the compact.

This has caused a lot of headache trying to decide what is best. I’ve ended up with a Z3 2.8 exhaust of ebay and Eisenmann backbox.

The following picture shows the left to right, presumably a 328i mid section, 316i compact mid section and Z3 2.0/2.8 mid section.

It turns out that the Z3 is about 260mm shorter than the Compact. So the mid section needed extending. We decided to buy a Mig welder and do the work our selves.

With a few hours practice with the welder it was time to give it ago. But first the exhaust needed to be cut in the correct place. This ended up being just after the Y join. Below you can see the gap after cutting and test mounting.

The new pipe section was tack welded then installed to check the fitment, with a few more tacks on the pipe joins the exhaust was removed again then fully welded, as seen below. Welds are not the best looking but I’ve only had a little time to practice.

With the mid section completed the Eisenmann was mounted. This required a hole cutting into the bumper for the new exhaust pipes. Once the cut was complete the backbox was mounted, we used some exhaust paste and a clamp to connect it to the mid section. The exhaust need’s a little work to fine tune its position. At the moment it is hanging a bit low.

Exhaust Bracket

Until now I have not had a bracket from the gearbox to the exhaust. The first bracket I ordered was supposed to be for a Z3 however it turned out to be for a 328i. This did not fit as the pipes on the Z3 exhaust have a larger diameter so the bracket would not go over. The next bracket I ordered was OEM z3. This turned out to be correct and fit perfectly. The bracket has helped to reduce the amount of resonance a little. However the resonance is still noticeable between 2500-2950 rpm once the engine is warm.