Well the first step on my slippery slope to Audio mentalism is complete. The components, coax, Sub and Amp are in and I can declare that the sound quality is worlds apart from the standard set up. I haven't had chance to clear out the boot yet (anyone want some VW speakers?) but you can pretty much see the sub and amp as they are at the moment.
First stage was Dynamatting all four doors and the boot to dampen out any unwanted distortion and insulate against outside sound. This has worked far better than I could have imagined, the cabin is a lot quieter than it was before with outside noise reduced. The vibration of the door cards and panels has reduced dramatically and generally the cabin is a lot nicer place to be.
Next, the speaker set up is simply stunning compared to standard. I didn't want a "blow your ears out" system and went for quality of sound instead. The components and coax give a lot more natural sound with zero distortion and great separation of tones and frequencies that makes the music sound more natural. For the sub I chose a 10" instead of a 12" as I play more pop and rock, rather than R & B style music and the 10" would have a better response to this. The fronts are more powerful too as they are driven from the 4 way amp rather than the head unit which gives a better balance with the sub. I am trying out 1 sub first to see if it is a good balance for the system before choosing to have the system better integrated with a custom build and so it is only in a boggo standard sub box at the mo and the amp is temporarily located on the rear seat back (no great shakes as the seats never fold down for large loads).
Source were very good and you simply cannot tell that they have been anywhere near the door cards (see pics) and so it looks totally OEM in the cabin. Boot is a bit messy for now, but this is only temporary.