what gauge wire to use

I am going to be using 2 gauge wire from the battery to my cap. Then 2 gauge from cap to distribution block. Then splitting to two amps. Should I run 4 gauge or is 8 gauge ok? Also since I have to run my rcas on my drivers side of my car is it okay to run the rca's on top of all the wires underneath the drivers dash...like over the ignition wires and stuff..or will that pick up interferance?

2 AWG might be way undersized or way oversized. What size fuse are you planning to use? You didn't give enough info. Year, make and model of vehicle Make/model of amplifier(s) Distances between Bat, Crap and Distro.

I will probably use a 160 amp fuse. 07 mustang, 2 power acoustic amps...total watts 1080 rms. Distance probably more than 12 feet. I know I need to use 2 gauge..my ? is should i use 4 gauge or 1 gauge from the distribution block to the amps?

Well, since #1 is LARGER than #2, it wouldn't make sense to do that, now would it? A pair of #4's from the distro to tha amps will be perfectly acceptable. BTW, 2AWG is far larger than you have to use. My math, at 50% efficiency (which is erring on the side of caution) gives me 150A which is perfectly safe for a #4 wire to carry, and #4 will also work (if very SLIGHTLY over-rated) with your desired 160A fuse. Power Akoustic, BTW, is a bit generous with their RMS ratings, I'd bet more in the 700 watt range, so, even there a #4 will suffice.It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."