Here is my current setup. It took me about 1.5 hrs on Thursday evening to route the power cable through the firewall and car. On Friday afternoon, I took about 1 hr and 45 mins to finish the rest of the setup. However I am not done yet, I rushed it because I had dinner plans and a soccer game later that evening. I would work on it now, but it's too damn hot in Houston,TX right now. My next step is to clean it up and make it look pretty.
The current setup is;
-760 watts max Sony xploid amp
-10" Infinity sub dual voice coil, (4 or 2 ohm, I forgot) - 500 watt rms / 1000 max
-ported sub enclosure
-low pass filter
I am using the left / right speaker signal and remote on signal coming into the factory amp.
My future plans are similar to spacewilly's idea. Get a space and power efficient 4 CH Amp, a smaller subwoofer and enclosure, run the door speaker off 2 ch's, and the sub from 2 ch bridged into one.
My current sub and enclosure is too damn loud, it rattles the whole car and the bass is too much.. lol. I didn't know it was going to be like this, I have the amp about 1/4 way turned on the gain, and the bass bumps super hard... anyways it'll do for now.
INFINITY 10" SUB + SONY AMP
LOW PASS FILTER
CABLE RAN UNDERNEATH REAR PASSENGER SEAT
CABLE RAN THROUGH FIREWALL FRONT PASSENGER FOOTWELL
CABLE RAN THROUGH FIREWALL - EXISTING GROMMET FOUND REAR LEFT OF BATTERY