I know I may be stepping on VP's toes by saying this, but IMO you should get an MS-8. Three reasons:
1. If you go with the Zapco amp, it has built-in processing, BUT it is large and dissipates a lot of heat so the install location will be a problem. Also, its processing capabilities are somewhat limited, and it does not auto eq. If you go with the Arc amp, you have virtually no digital processing whatsoever.
2. If you go with the MS-8, you can use a small digital amplifier and tuck everything away behind the trunk panels without compromising looks, space, and cooling.
3. The MS-8 allows you to implement and power a center speaker which greatly enhances both imaging and tonality of the front stage.
The street price for the MS-8 is around $600 and a you can get a good digital 6-channel amp for under $400 (JL XD600/6). With the MS-8 and Logic 7, you do NOT need high quality speakers in the rear of the vehicle, so you can save the price of those Morel coaxials and just leave in the stock HiFi speakers.
Just my $.02. Ken, don't flame me...