What should I use to make my VW sound great?

I have a 2006 VW GTI mkv and I want to upgrade my sound system. First of all, I dont know wether I should or Shouldnt keep the stock head unit. It has a six cd changer, and I like it a lot, but it is only 20w x 4. If I were to change that, I would replace it with the new Apple/Alpine head unit - 50w x 4. Basically, I want to know what speakers sound great with either of the two head units. Any suggestions?|||speakers will sound great but will deteriorate way faster if you replace your stock unit with the alpine. that is going to be twice the RMS power going through the speakers. (RMS is continous power/watts given to the speakers). therefore you are going to have to replace the speakers with a higher RMS input. if you are going to put amplifiers you definitely need to replace the speakers. do it professionally so you are covered in case of anything going wrong. good luck|||get new bose in side like u have im gessing 6'1/2 in the front doors and upgrade to some 6/9's in the back then get one 12 kicker L7 with a kicker 2500 Amp GET A ALPINE deck that powers mids and highs good