Project E36 323is: Building the Poor Man’s M3, Part 4 – Exhaust

Project E36 323is: Building the Poor Man's M3, Part 4 
– Exhaust

By Jonathan Lawson

Now that our E36 323is is hustling through the corners a bit more sure-footedly, there's one thing that seems to be missing.  A soundtrack!  While our car is not packing the most powerful engine in the world, it's still got a bullet-proof and (potentially) great sounding BMW M52B25 inline 6, yet it's almost as if the factory put the whole car on mute.  The engine loves to rev, and is sewing machine smooth at any RPM thanks to the motor's inherent balance, but it really feels like it wants to sing a bit louder, and who are we to stop it?
E36 Corsa exhaust and M3 center section
The good folks at Corsa have just the cure for us.  Pictured above is our new exhaust system for Project E36 323is.  That's the Corsa cat-back exhaust in the background and our “new” E36 M3/328i center section in the front.
E36 323is center exhaust section
With the design of the 323is center section having dual pipes going down to a Y before the cats, we already knew we wanted to change over to the fully-compatible M3/328i section in order to get some better flow while maintaining the catalytic converters (legally required in CA).  
E36 M3 vs 323is center section comparison
This is a better view of the center sections side-by-side.  You can clearly see the difference once you get to the cats.  What once was a Y is now a set of twin pipes all the way back on the M3/328i version.  Not only does that help to increase flow a bit, but it also just happens to open up a very wide range of choices in cat-back exhausts.
E36 Corsa exhaust versus factory 323is comparison
Our exhaust choices were plentiful and many of them met our criteria for weight reduction, which isn't too hard when comparing to a bulky OE muffler as shown above.   Our stock muffler was 43 pounds, so we managed to cut off around 10 pounds with the Corsa, and if looks matter to you, this one's got the goods, especially with the new Diamond Black finish on the tips. 



  1. This is really dope, but I have a question regarding the O2 sensors and wire harness.
    I know for the 323is exhaust there are only two O2 sensors. One before the cat and one after. but on the 328 exhaust theres a total of 4 because of the dual cat setup. Did you have to use the s52 wire harness for this setup? I did this exact same engine build on my 323is and im wondering if the s52 tune I have on my ecu will run properly with my standard 323is exhaust

    1. Curious to find out too about the o2 sensors. I am looking to do the same with m3/328 downpipe all the way to the muffler. Also wonder how much power gain in real world (0-60 time).

    2. I did this exhaust swap on my 323ic and now have an engine code P0133 after relocating the single pre cat sensor to one of the headers. I’m at my wits end and don’t know how to fix this issue without getting a whole new wiring harness for my car. Anyone else who’s got an idea of what to do please reply.

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