The current Pioneer Sub like that one (TS-W3002D2) goes for $150 plus shipping.
SonicElectronix.com I've got a baby Pioneer 10" in my TA with a 400watt Alpine Mono-D and it works great, no complaints.
The Memphis amp seems to be going for around $480 on line. Don't know anything about them but the specs look good.
I assume the Pioneer is a dual 2ohm, so you would be running in parallel for a 1 ohm load at the amp. That amp is rated at 1000watts @ 1ohm. Should wake up the neighbors pretty well. The cap might help keep your lights from dimming on bass hits a bit.
The weak link is going to be the head unit.
Check this out: http://www.grandprixforums.net/06-mo...rap-36872.html
You are going to have trouble with the 6x9's because the Monsoon rear speakers are bi-amped. If you are crafty you can probably rig it up by cutting the tweeter leads and wiring them separately. Just make sure the cap is still in the circut. I'd also suggest putting caps on the 6x9 woofers to keep them from bottoming out.
If you can listen to it before you buy it, and your buddy knows what he is doing looks like an OK deal.
My $0.02.
