I'm running the HSK163.4's. Awesome speakers.
The factory VW radio's, no matter RCD310/510 or RNS510 do not produce enough power to make them really sing. Match them to a 4channel amp that fits under on of the front two seats. ARC Audio KS300.4 or similar. I think the new V power amps from Alpine may fit too. This will really make them sing.
In Addition, since the door cards are coming off for the speakers. Remember to install sound deading in the doors and around the speakers, don't forget the door cards too. lol
This will not only improve the sound, but will have less road noise in the car and make the speakers sound even better.