The installer that I used, Marty Price at FHRX, left the existing head unit in place with all of its normal functionality. He then replaced the tweeter and bass with German Maestro speakers, replaced the existing two subs with two Focal 8 inches, and drove everything through a helix processor/ amplifier.
Key things. The maestro bass and tweeters went easily into the existing door and pillar spaces. Secondly the helix went in easily underneath the driver seat. Thirdly all cabling needs to go down the driver's side because there is existing cabling on the other that can cause interference. By doing it this way all of the existing functionality through the OEM head unit was maintained. I challenge anyone looking at my vehicle interior to spot that there is a very serious sound system aboard.
This approach might be of use to someone thinking about how to improve the existing sound system.
Two other things. Marty sound proofed just about everywhere, such that some of my passengers are not aware they are in a v8 [For those of you who think this is sacrilege put the window down a bit].
Secondly, my vehicle is the series 2 vf ute. Perhaps that is an odd choice of vehicle to go high end on but if you are doing a lot of country miles there is no doubt they go quicker with quality music. For those with a ute doing some serious miles this is a relatively easy improvement.
