I got the 5 degree C fan mod performed at my local Mercedes Benz dealership last week. They charged me for 1 hour of diagnostic time.

It works exactly as I requested. The fan comes on when the coolant gets up to 88 C, and shuts of when the coolant drops to 87 C.

I have only driven in cold temperatures so far. It's too soon to tell how much it is helping intake air temperatures.