I had a DSP amp water got in and it died. I never took it out, mounted a 4 channel above it to run my 8 factory speakers, tapped into the remote wire and spliced into the speaker wires right there at the dsp amp. Changed the head unit and added another amp opposite side in the rear as well (removed the factory subwoofer box) and mounted amp there to drive my subs. Its' about a 6-8hr job. If your really good, maybe 4 hrs. I switch my subs from three 12" woofers to a single 10" apline depending if i need cargo space!

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2003 BMW E53 X5 4.4i - M62 engine (Non Sport with Premium and Cold Weather Package)
Color: Steel Gray Metallic
Mods:4.6is Exhaust (Pipes, Mufflers and chrome oval tips) BMW Sport package Taillamps, BMW Tire Valve Stem Caps
Medium tinted front windows
JVC HD Radio
Alpine 4x100 channel Amp
Orion 600W Mono HC Amp
Three 12" Sony Xplode in subwoofer enclosure