[Alscoob]

On my last 340i I fitted the MPPSK chrome tips to my standard back box. They are much bigger than the standard and are OEM, so subtle and not looking too Jap stylee

To fit them you will also need the step adapted pipes from the 140i and will have to cut the existing pipe projection so that it's not seen poking through the adapters. You have to fiddle a bit to align them but to me they were a great addition. Couple of pics of the process if it helps?

Of course if you want to set them further under the car you can just trim the adapter sleeve where its on the existing pipe (narrow end). I clamped them on so I could remove again if I wanted, but never did, so guess you could just spot weld them in position?