Here is the info I could find quickly on the C32 to SLK32 brake swap. As I find any additional info I will post it.

Intriguing mod for the SLK32, but the degraded performance may be caused by...

...here are my theories...

It's quite possible that inferior performance may have been related to the switch to a new flexible brake line.

If the new adapter hose itself or the end fittings connected after the installation of C32 calipers onto the SLK32 has a flow diameter slightly smaller than the original hose, pressure drop can increase! The smaller braided hose may have been used to compensate for a longer hose length with the thought of equaling or reducing unsprung weight.

Once pressure drop increased, reaction of the calipers can be minutely slowed and the applied force on the pads relatively decreased as well.

There should have been an improvement on the SLK32's braking or stopping distances with the C32 brakes' larger swept area! Those brakes were designed to stop a heavier car.

Another item to check for is any difference in the designed boost pressure between the C32's and the SLK32's brake systems. It's entirely possible the C32 has a higher applied brake system pressure rating.

The logic for these technical theories are based on basic hydraulic system design principles! Maybe Tim's friends can try again. Hope this helps!