Here is a build I did for a buddy of mine.
Nothing compared to the sound output you guys are used to, but it was my loudest system I've installed.
It was for my buddy that was stationed overseas in Iraq.
It's his first car he's ever paid off (he has a totalling habit...so this is car #7)
Misc Stuff:
RePainted Wheels to match body colors
Tinted Windows
Smoked Taillights and Corner lights
Custom Projector Headlights
Full Interior Custom LED Upgrade
Audio:
Kenwood KDC-X994 Deck with iPod, Bluetooth, and HD Radio built in.
Memphis Audio 6.5" Syncro Componant Speakers up front
Memphis Audio 6x9" MClass Coaxial Speakers in the rear
Memphis Audio MClass 300 watt 4 channel amplifier
Memphis Audio Dual 12" CM Subwoofers (1100 watts RMS each)
Memphis Audio Dual 1100 watt mono block MClass woofer amps
Dual Stinger 1500 watt batteries
DC Power High Performance Alternator
'Big 3' wiring upgrade in the engine compartment
200 sq.ft. of sound deadening throughout the entire car