E46 BMW M3 Turbo: Part 2 – Splitter, diffuser, 3.5-in exhaust, and dyno testing!


Starting with the splitter, installing this unit is actually very simple.  The instructions recommend applying some Werth adhesive to secure it.  You won’t need to put any adhesive of it on the carbon itself.

Once fitted, just make sure you can maintain pressure on the splitter against the bumper for about an hour. 

We went the extra mile by installing machine screws and washers so that the diffuser cannot come unglued at high speed.  Notice on the left (passenger) side there isn’t a screw in the middle.  That’s because you don’t want to drill there—or you’ll put a whole through the windshield washer fluid reservoir.  Aren’t you glad we know this?  It’s either because we’re so smart, or because we may have accidentally done this to our own Project E46 M3 and got coolant all over our faces.  You decide.

In the picture above, notice the underside of the splitter, which isn’t carbon weave.  This is good, especially for lowered cars, because the clear coat on “wet” carbon will scratch and crack easily if it meets a curb.  This gives you some added piece of mind when going up those driveways that are so steep that the even the best angled-entry method doesn’t avoid some contact between the splitter and the cement (why can’t homebuilders make our car-dork lives easier?).


As you can see, it’s the same splitter as the one installed on our silver Project E46 M3.  It’s a simple install the makes the front of the car look much better.

And now it’s time to get after the rear exhaust and diffuser.  To give you a visual of where we’re starting from, here’s a picture of the car with a quad-tip exhaust from Rogue Engineering.  The overall setup looks good, but some could argue it’s looking a little plain.

You may recall when we added a small diffuser to our Project E46 M3 in Part 10 of that series.  The aesthetic difference was significant, making the rear end of the car much more pleasing to the eye.  It’s still noticeable every time we walk up to it.  This diffuser from BImmerWorld, however, should be at a whole other level.

Leave a Reply

Your email address will not be published. Required fields are marked *