IIRC the NQS BBK Calipers are from the Porsche Boxster 2.5 & 2.7.
Taken from DaveB's thread....
The part numbers you need are 986 351 421 & 422
Just a brief explanation of part numbers:
First three are the model number 986=Boxster, 996=911, 955=Cayenne
351 = Front brakes
421 Left Caliper (odd numbers) & 422 Right Caliper (Even numbers)
Dont buy anything with a 352 in the part number they are rear calipers and the pistons are too small for a Mk5