Digit-Power. A swiss company. The power upgrade is in the form of a more powerful pulley.
This was installed to my old SLK (a 2.3 liter Kompressor). As you might know, the Kompressor is a supercharger, and the supercharger works by pushing compressed air into the pistons. This in turn is done by the pulley.
The standard pulley will cause the supercharger to work at a certain force. With the upgraded pulley (about $1500), they replace the original and thus increase the power of the supercharger.
This means that the new pulley is able to push even more air into the engine, and thus you get more power.
On your 350, you will not be able to do this since it's an atmospherically powered engine. It has no turbo or pulley... You can however do it on the SLK 200 (R171) since it uses a pulley. Apparently, some companies (Brabus etc), are able to bring power up to around 190hp.
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