Steve:
Activation for the IHI used in the Merc SLK AMG and in the Crossfire has an electromagnetic clutch, and is triggered by rate of acceleration and RPM. The ECU has a memory, like in VW products that determines when the belt driven compressor kicks in. So it responds differently depending on how you drive. I'm not sure what you mean by "coming on cam", can you let me know? Your car weighs 150 lbs less than mine, but has 145 less hp and 110 less ft-lbs of torque, according to manufacturer's data, which we know is always true. While I have never driven a 230, I think they drive a bit differently, although I think the superchargers work similarly. I do think your car looks nicer than mine though, especially from the front, and I'm sure the interior is more plush. The Crossfire was a Merc hand me down, and doesn't have all the plush MB amenities. I actually got the term "blower" from reading a Brit book when I was a teenager about Bentleys with the Roots supercharger in them.
Supercharger
From Wikipedia, the free encyclopedia
For other meanings, see supercharger (disambiguation)
A supercharger (blower) is a gas compressor that forces more air into the combustion chamber(s) of an internal combustion engine than is achievable with ambient atmospheric pressure (as seen in a naturally-aspirated engine, see forced induction). The higher mass flow rate together with an increased heat input provided by additional fuel combining with the greater mass of atmospheric oxygen available, increases the specific cycle work and hence power output of the engine.
A supercharger can be powered mechanically by belt, gear and shaft, or chain-drive from the engine's crankshaft. It can also be driven by a gas turbine powered by the exhaust gases from the engine. Such turbine-driven centrifugal superchargers are correctly known as turbo-superchargers, or more commonly, turbochargers.