Their web site will give you the power and torque increases. Looks like another 59 bhp for your C350, which will make a noticeable difference to the car!
I'm happy to work out the theoretical top speed for you if you supply:
engine power (at the flywheel) in BHP* or engine power (at the wheel) in BHP
vehicle track and vehicle height in m or maximum vehicle cross sectional area**
vehicle mass (kerb weight) in kg
drag coefficient (Cd)**
* transmission losses will be assumed to be 18% unless you specify otherwise
** remember this will be altered by modifications, but it's unlikely you'll find anything other than the official factory figure.