is that 800W a max power rating or RMS? if it's max, you shouldn't use that number to consider the amp needed. you should use the RMS power as a general idea of the amount of power needed.
are you saying the subs are 400W each and 800W total? or 800W each?(I doubt this with the audiobahns)
what is the resistance of the subwoofers? that will dictate what kind of amp you will need along with the power rating of the subs
dual voice coil(DVC) or single voice coil (SVC) on the subs?
You will need to get another amp for the interior speakers, especially since you will want stereo sound. Depending on what speakers you get for the interior, using your HU to amplifiy them might work for the time being. Getting a quality cd player(HU) makes a big difference in what those interior speakers will sound like
Dual 12" Molded, Textured Injection Poly Cone 50 oz Strontium Magnets 2" 4 Layer ASV Voice Coil Power Handling: 800W RMS Sensitivity: 103 dB Frequency Response: 25-140 Hz Impedance: Dual 4-Ohm (two 4-ohm terminals can be wired together for a single 2-ohm load)
lookin' at the specs, that amp is 1Ohm stable so you'll be able to wire it to get the full 1200W out of the amp.
Kicker amps are highly regarded by the people on this forum and are known for their quality.
I'm not too familiar with audiobahn subs, but in general, sending 600W to each would work just fine. most subs will reach their maximum excursion before the continuous power maximum (which is usually thermal anyways), so only giving 600W to a 800W sub should work just fine.
as an example, the adire shiva can handle I believe 650W RMS and works just fine with about 300W supplied to it.
