Time to ask for help again. Apparently there is no difference in the E55/CL55 exhaust system, so all that is left to account for the performance difference is the air intakes.
On the E55, the right air intake tubing(facing the front of the car) narrows considerably to navigate around some engine piping just after the air intake beside the radiator.
Is this the same on the CL55??

 

I believe I read somewhere that the E55 makes a little less boost pressure from the S/C than the CL55/SL55 and S55. This may be where the power difference is.

 

The boost pressure is the same. The official line is that it is an intake problem caused by lack of space in the engine bay.

 

Are the ECU's the same and or have different programming?

 

I thought I had read in several places that the E55 has 70mm exhaust piping the the SL/CL/S have 90mm exhaust piping. This difference is what causes the power difference.

Of course, I have also *heard* that the cars are all dynoing about the same anyway, and that the purported 30 hp difference is nothing but marketing? That was just a rumor, though.

 

After a lot of research I have discovered the following;
E55 exhaust has crossover pipe after second cat, CL,SL and S do not. Exhaust systems otherwise pretty much the same.
E55 has large king in right hand side air tube, which also only has about 1/2 the surface area on the intae tube as left side. S500 airtube can be made to squeeze in and fix this problem.
My car should be fully de-restricted next week!
I don't know however how much impact this really makes powerwise, because I believe that they are all putting out pretty much the same power anyway.