I've just remembered something. When I transferred the engine over to this chassis I did not transfer the ignition control module with it. I implicitly assumed 103.983 RUF engines would have the same modules but looking at the mercedes EPC tells me this is not the case. Now my current chassis has p/n 0055458532 installed, I'm not sure what the original chassis had, I hope mercedes can tell from the chassis no.!

Does anybody know what difference these p/n have? I'm guessing they have slightly different ignition maps for the same R16 values which perhaps explains why my car runs better at "2" than the "N" stated on the Brabus plaque. However I didn't think that more retarded iginition could cause problems, only that advancing it too far could? I'm confused!