Hey guys,I'm purchasing a few things for my 2003 GTI and I was wondering how much of a difference (quality wise) a head unit would be. I was suggested Alpine CDA 9887, but was wondering if it would really improve the sound, or should I just stick with something cheaper, since I am in school and kind of strapped for cash to get a head unit with all that stuff. What I plan to purchase: Helix HXS 136 Esprit Sundown SAX-125.2 Fi Q12 Diamond audio D3 800.1 or Sundown SAZ1500D(used) Cheers!