Do you know if its the front or back that's over heating? Use an inferred thermometer to shoot the rotors immediately after you experience the brake fade, so you can identify the temp, F or R or which corner of the car is getting really hot. If its the front brakes you can try adding
Porsche GT3 Brake Scoops to direct additional air into the inner wheel hub area to cool the brakes, 5 Years ago they were like $11 each side so they wont break the bank and can be adapted to fit in about 20 minutes to the MK6 using a drill, sharp scissors and some cable ties. Once you see the pics in the link you will get the idea, a few degrees of cooling can make all the difference