What side should I run cabling?

You can run it on either side actually. It does not need to be separate from the power. AC current will readily induct noise, DC is by far a different story altogether. Is it good practice to run them separate, sure it is as it also keeps a big bundle of wires from forming under the carpet. As far as running the wire under the car goes, not a good idea unless you have 100% secured the cable every 6" or have encased the cable in some kind of hard tubing. A zap strap or plastic loop is not enough to properly secure the wire to the bottom of the car. In time this wire will droop and catch on a speedbump or an obstacle on the road (like a flapcat from the roadkill cafe). Top Secret, I can tell you but then my wife will kill me.

I run my 0 through conduit (home depot) under my car. This is the best way I have found. No problems so far. After that RCA and speaked wire is a breeze. Put it where you can fit it(safely)Mazda 323 GTX +

330 lbs. glass +

4, 5 gallon buckets resin +

1600w RMS @ 1ohm = 162.3db

i have always found that it is a good idea to run the RCAs on the opposite side of the vehicle. especially if your not using a high end rca because in some cases running them together causes alternator whine interference. 2007 Acura TSX

SQ setup in the works