read on.....
The Official C32 Throttle Body Thread - MBWorld.org Forums

b22b

 

2 year old thread.. I'd have to guess things didn't pan out too well.

 

To equip a larger TB in the stock position on the 6, the SC snot inlet will have to be enlarged and something will need to be done about the gasket. I don't think simply enlarging the TB is the answer because that's only 1 of 3 parts at 74mm.

 

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......

 

and another interesting twist to throw in the mix....
----------------------------------------
MBWorld.org Forums - View Single Post - Another 82mm t/b install

 

and if you want to go with the bore/grind/polish..
talk to Exotic-metal55
74mm TB shaft grinded to 5mm complement of Exotic_Metal55 - MBWorld.org Forums

seems like it might be fruitful contrary to RobertAMG's outcome 2 posts below.

b22b

 

Although I'm still researching here's what I've gleaned so far.
Constructive Objections encouraged.

Practicalities
You can go for an Audi S4 82mm TB PN077133062A for $150-$200 (2nd hnd). Plenty of them around.
You need to rewire the pinouts and maybe add a connector.
I'd seriously consider getting some work done on it also - like shaft/porting and polishing.

To reap full benefit you need to change your SC snout to the post 2006 SL55 type of PN1131400912
That also will need to be ported and polished and the bypass valve plated/smoothed/streamlined for our application (no bypass).
Then you need a 6mm adapter plate between the SC inlet and the TB.

Then of course comes the Y-Piece and intakes.
I understand an 80mm PN 1130900329 will do it,
but intake suppliers may come to your rescue here with a suitable 82mm Y-piece to fit to their DCAI.
But you can work your own around the 1130900329 if you're up to it. But it has oval outlet hoses....so tricky.

Performance gains....
My calcs suggest maybe 4-5rwhp on an SLK32 61/155 setup since you gain an extra maybe 0.5psi at WOT. But given the DCAI is adding 7-10rwhp (and reportedly better low end improvements), that's not a shabby extra if you can DIY it cheap enuf.
The E55/SLK55 guys are talking it up. EC is even claiming 40rwhp on their website for the 55's....I cant see it - breathing must be a particularly weak link in them if that is the case.
here
Given our 61/155 setups with a few other mods are nearing the stock 55 cfm, I would imagine our efforts maybe similarly rewarded.