AMP3 in my car for 8" subs

Hi new mustang came with 2 8" door subs and 2 crummy little amps, about 100W each. The factory woofers are 2 ohm DVC but I replaced them with 8 ohm Seas CA21RE's -- needless to say I need new amps. I think I can make 2 AMP3 kits from, each bridged for about 50W into 8 Ohms.

What I'm curious about are the details, since I'm very new at this. The factory amps are hooked up with harnesses, so I need to figure out which wire is which and how best to connect them to the new amps. I also need a way to determine if the factory amps are using line-level or high-level inputs; they look like speaker cables going in, but it would be good to be sure before I shell out for a LOC.

Finally, what else do I need to know here? :)
So, I'm basically looking for a kit that will do 2x100W @ 8 ohms, give or take. I'm also open to just buying an amp since the kit options seem limited.

What's my best option? a 2-channel that can do ~80-100W into 8 ohms per side, or a monoblock with 200W @ 4 ohms, both woofers wired in parallel?

You're probably right...still, I'm hoping to find a solution that will work as close to PnP as possible for now, and maybe upgrade later.

Tripath recommends their's the new 4x100W head unit chip. Hot stuff. Unfortunately not bridgeable but I imagine I could find something to do with those extra 2 channels. Unfortunately I have not seen any kits for it yet :(