• The tiny factory-fitted 4" speakers in a 70 Series are mounted underneath the dash, firing down towards your feet.  Larger 6" speakers in the doors with custom mounts are simply better, and the tweeters give us more control over where the sound appears to come from (higher up closer to your ears instead of somewhere below the knee).  The components in this system start from $899 a pair.
  
  
• The sound deadening helps reduce acoustic loss.  The door acts as a speaker enclosure, and as the door skin vibrates, the energy turned into sound gets lost as vibration instead.
  
  
• We will run the new rear speakers from the head unit, but the amp drives those new front speakers.  The head unit, either the factory Toyota or an upgraded unit simply doesn't have enough grunt to make the most of the speaker upgrade.  The amp delivers the power they need so that it sounds great WITHOUT pushing the head unit too much.

• The fullsize subwoofer and enclosure is still slim enough to sit on the rear wheel arch, or behind the rear seat in dual cabs.

Brands involved:

Key items in this system may include Alpine Status, ZeroFlex, Hertz, Zapco, Harmony, JL Audio, ESB, Sony ES, Rainbow, Audison, and Focal, among others.