I recently picked up and M2 exhaust to install on my M240i. I kind of took a gamble because I was unaware of anyone else doing this and I was not sure exactly how it was going to fit. I figured that no matter what I would end up with a quad tip exhaust which is what I think this car really should have.
I was hoping I could cut the pipe where one would cut for an M performance muffler. I tried that and it was not even close. I realized that the M2 pipe is quite a bit different and more direct than the M240 pipe.They end up coming together at roughly the same spot forward of the resonator. The resonator on the M240 is almost twice the size of the one on the M2, which I believe is the same as the M235.
Here is a picture of the M2 exhaust on top of the M240:
As you can see the M2 pipe is quite a bit straighter. The M2 muffler is also quite a bit narrower. After working through this I realized that the brackets that support the mufflers have different part numbers and are different.
The M240 bracket is on the top and the M235/M2 bracket is on the bottom. Unfortunately I had to purchase these new from the dealer and even with a discount they were $45 each. But once I got these brackets everything lined up nicely.
Part #'s:
Right 18307620317
Left 18307620316
I welded everything back together where I had cut it initially and then welded it in place in front of the resonator.
It was quite a bit of work but I managed to combine and M2 rear diffuser with an M240 diffuser. I am considering this my first prototype on this because it did not turn out quite as nicely as I had hoped. It looks really good but does not fit quite right in the middle where is snaps in place.
Also to make everything fit I had to fabricate a simple right angle bracket between the heat shield and the new diffuser to support the diffuser in the middle.
I would say the sound is roughly 20 to 30% louder and deeper than stock. In comfort mode it sounds quite similar to the 240 but a little bit louder. In sport mode it is quite a bit louder and there is lots of burbling on deceleration and down shifts. I would say it sounds closer to an M2 than an M240 now.
At idle it is quite a bit deeper and richer sounding.
If anyone else wants to do this I can certainly offer some advice. You would need to get the brackets and have somebody weld it together up in front of the resonator. I would not just clamp it there because the pipe is not supported in either direction for quite a distance.
There may also be some other quad tip diffusers out there that you could buy off-the-shelf and would fit. Perhaps someone will manufacture one.
After I make my next diffuser I may look at bringing it to a friend of mine who could make some molds of it out of carbon fiber.
I also think I picked up a little power with this as well. I have snapped of a 3.8 0-60 time with it. I did not have the laptimer app working before so I have no direct comparison.
Here is the video:
https://youtu.be/6POMUR78UKU
Pat
