Project E46 M3, Part 17: Preferred exhaust, MKC/AEM tune


When it was all said and done, this is how we ended up. We left our last test with the new clutch at just under 314 WHP, and left today with just shy of 316 WHP, but with a lot more torque down low.

This is where we had to start today with the AEM start-up map. This is over 23 WHP and 16 lb-ft later. While we used to use STD correction early on in our project, we only use SAE as the new Winpep program, which is the Dynojet’s software, doesn’t allow STD. SAE is a correction for 77F, while STD is 68F, thus, showing a few more ponies. In STD the power would be 322.

Considering we’ve got four different exhaust companies involved, including VAC headers, a Megan Racing Section 1, a factory BMW Section 2, and a Scorpion Section 3, we’re rather impressed by the fitment. It’s pretty close to perfect, and is the setup that will stay on this car for a while.

After all of these different combinations tested on the exhaust system, I think we’ve found the right one for Project E46 M3. Check out how quiet the start up is—remember, this is cat-less! The drone is almost completely gone, and the car is much more pleasurable to drive. I had a chance to follow the car, and as long as the car is at part-throttle or less, it sounds very close to a stock E46 M3. At full throttle, you can hear the buzzing-bee note out the back, although it’s at a deeper note than stock. At last, we’ve got a free flowing exhaust combination that is light, quiet, makes power, and fits really well!

One of the reasons I was excited about installing the Koyorad radiator in Part 16 is that I knew it would help keep our dyno runs repeatable. The car never exceeded what you see here for oil and water temps—the latter actually being below the halfway point but we’re at the wrong angle to witness it. In fact, according to our AEM readout, the coolant temps stayed between 165-180F the entire day! It would only climb 12-15F after each run, and quickly come back town to 165. The car is using a factory thermostat.


  1. Dear All
    Just read your exhaust articles on the E46 M3. I’d like to replicate what you did with the VAC / Fabspeed headers, standard cat section then Corsa cat back. I’ve looked on VAC’s website but they only appear to sell Active Autowerke Performance headers ( Can you comment on this please? Do you think I’ll get the same / similar results that you did. I would like the slight improvement in power, no drone, decent quality and fitment, etc. My car is mainly road going with some track days.
    Thanks in advance for any help.
    Kind regards, John

    1. hi John, the droning issue will be taken car of at the mid-section and back/muffler end of the exhaust, especially the back. As long as the AA headers are similar fitment (legnth-wise) with the previous Fabspeed/VAC units, you should be fine, and I would assume make similar power, too. But that’s a question for VAC. Personally I’ve never had any problems with AA products, and I ran a lot of it in my earlier “E36” days. All of their exhaust stuff fit well, too. And if you still decide to go with Fabspeed, may just have to get them direct, is all, if VAC doesn’t carry it anymore. Thanks for reading, and best of luck!

  2. Thanks very much for the response. I have emailed Fabspeed as it looks like they only do left hand drive fitment but mine’s a right hand drive. Will see where this goes. Appreciate your help.
    Regards, John

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