Okay in no way would you ever in a million years need 2 gauge wire to run an 800 watt peak amplifier. ZR1 ( i ****ing love that car by the way) the chart that crutchfield puts out is based on watts of rms power not peak, it isnt your fault that the chart doesnt specify it. If you were running 800 rms you still wouldnt "need" 2 gauge but it would be alot easier on the amplifier.
Sadly Sony does not make very powerful amplifiers. I'm certain that amp wouldn't even need 4 gauge much less 2 gauge. That sony 800 watt is a joke at best.
If you read it specs it only puts our a measly 250 watts rms total at 4 ohms. and maby 300 watts at 2 ohms, Even these numbers are probably overestimates. From my experience 8 gauge would handle that just fine. And if your worried pick up the 6 gauge kit i mentioned from walmart. Its cheap and its 100% pure copper unlike these power acoustics kits.