I think Loungn14 did something like this (from the thread below)....here click
but cant work out if it was just a bore out of the existing or a full replacement TB.

Just been through the thread...click here
as usual - many confusing PN's and interpretations.
If someone is going towards the SL55 intake boxes etc....then be worth considering at least an 80mm TB and SC Snout (PN A1131400412) and adapting, but the power gains may not be there acording to Key3 below.

I found 3 posts to be key within this thread;
Key1
http://m.mbworld.org/forums/showpost.php?p=4556843&postcount=16
From what I have read, the cl600 throttle body should be a 80mm tb. You would need to port the opening of the rear supercharger housing to 80mm or you could buy a new rear supercharger snout from a 2006 sl55, apparently the supercharger snout is already 80mm. You would also need to change the pins for the the throttle body cable, so that the blade opens correctly. Read through this thread and you should be able to find a majority of the info

Key 2
http://m.mbworld.org/forums/showpost.php?p=4556886&postcount=18
Does anybody know if the e55 rear supercharger snout would fit on the C32? I have compared them up close and they seem to be about the same size, but there are a few differences. I'm going to see if some one could help me modify the e55 super charger snout and then maybe I can get started on this project

Key 3
From RobertAMG
http://m.mbworld.org/forums/showpost.php?p=4613293&postcount=40
i have installed successfully the 80mm tb of the V12 NA on my C32, i am running it now on the car from 1 week with no problems no codes, the AFR didn't change, maybe tomorrow or next week i'll go to the dyno and see it made more hp or not
.......then
http://m.mbworld.org/forums/showpost.php?p=4615032&postcount=42
TB part nb: 137 141 01 25, you have to swap pins 1-4 and 5-6 that's all, also i didn't cut any wire, i swap the pins inside the hardness.
i attached pics in the thread " dyno results".
of course when i mentioned no afr change i mean at full throttle at fourth and fifth gear to 150 mph not at idle!
.....then
http://m.mbworld.org/forums/showpost.php?p=4616365&postcount=44
I went today to the dyno, attached is the dyno sheet, run 3 is the best run done before without tb, run 5 and 6 are for today, so no difference in power with the bigger tb, slightly down hp.
The boost is the same, AFR the same and hp/tq are the same. the 74mm tb is sufficient on my car.
the bottom y pipe is the stock one, i didn't touch it
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I find the fact that RobertAMG didnt see an increase in power, strange.
Oh Well......