There is really nothing to it. I did a custom system on mine about a year ago. I have a pioneer head unit, 4 alpine speakers (all 5x7 to fit in the original speaker holes), a 10in JL sub, and an audiobahn amp pumping out 400 rms. The only thing I had a problem with, until I figured it out, was that if you are going to use the original wiring for the four speakers in the doors and on the roof, you have to make sure you connect the blue amp remote wire for those speakers. The original system in pathfinders have amps already built into them. The amps are located in the right rear cargo area. So unless you want to rewire the whole truck, just make sure you use that bule wire already set up for the amps. The blue wire is in the wireing harness with the rest of the speaker wires. Now, to use those amps and your sub, you have to rig it to where your amp remote wire and the other amps remote wire go to the same connector on your head unit. For the 4 gauge wire that I used to power my amp, I had to put it thought a small hole located in the front driver side firewall (real close to the battery). It was coverd by a small, plastic, black cap that could be easily pushed out. I had to bore the whole out slightly to get the wire to fit thourgh.