Why don't you just get the harness adapter? Crutchfield makes one, and I know there are other sources. It plugs into the wiring at the amp, and should be long enough to reach the trunk, or wherever you mount your amp! This way you can always return everything to stock(i.e. not cut wires)
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1999 SE V6 MTX
Borla Cat-Back(welded on w/clipped Cat)
Enkei RS6 wheels/Yokohama AVID H4 rubber
Clarion CD head unit
Clarion 6CD changer under passenger seat
MTX 10" subs in sealed enclosure
2 MTX Thunder amps (1 200x2, 1 100x4)
Cerwin Vega 5x7 plate 3ways
ASC Power Moonroof (like the controls better than factory)
Medium Steel Blue Metallic exterior
Moonlight Blue Cloth interior
Limo Tint rear 3 windows
35% tint front doors
KKM True-Rev
Energy Suspension bushings/inserts(on order)
2000+ cupholder insert
TH Fix
Fog Light Fix