Yeah I looked at the SPG, but honestly in my experience those monster type subs require too much power to sound good. The D5 is much more efficient and besides I'll be sticking with the stock sound system inside the car so I don't want to overpower it too much anyhow.
And the amp I'm going to use is an Akai ACA-2104 http://www.akai.com/product_detail.a...id2=24&id3=161
This is a low price amp that puts out a good 800 watts RMS at 4 ohms in bridged 2 channel mode. I've seen reviews that put it on par with 1200 watt RMS Audiobahn amps. But still I'm not positive it will be enough for the D5's so if it doesn't hit hard or clean I'm going to man up and get a proper Earthquake amp.
I haven't decided if I'm going to go with a 2 fared capacitor or run a 2nd battery. I really hate adding a ton of weight so I'm leaning towards the cap....either that or get a lightweight battery for my primary and use the stock battery as the amp power. In fact I'm so concerned about adding weight I'm considering making my own custom enclosures from fiberglass instead of the mdf Boston boxes.