Upgrading car audio

[jack_maxwell]

Hi,
Looking to upgrade the speakers in my mk5 golf. I was wondering if these hertz speakers (Clicky below) were any good and if they would fit in the front doors of the car? I am imagining that some sort of MDF adapter will probably have to be made. I am also wanting to know what amplifier to get to power the speakers, preferably a hertz one that could power both the front doors and also power 2 speakers in the rear door for future mods.

I have upgraded my radio to an RCD510 Dab

http://www.ebay.co.uk/itm/HERTZ-HSK163-16-5CM-6-5-HIGH-ENERGY-3-WAY-COMPONENT-CAR-DOOR-SHELF-SPEAKERS-/161076809690?pt=UK_In_Car_Technology&hash=item2580ed0fda

[jack_maxwell]

Im guessing this amp could be used (completely new to all this car audio stuff)

http://www.hertzaudiovideo.com/default_en.htm