OEM Deck with add-ons: Advice?

[GreenSpeed]

OK guys-

I'm not an audiophile, but want a little extra sound output from the OEM deck. I may upgrade later to a better system, but the wife drives the car a lot and definitely doesn't appreciate thump.

I was thinking of getting a slim downfacing sub enclosure (to fit under the passenger seat) as well as a shallow 10" sub....links below:

http://cgi.ebay.com/10-UNDER-SEAT-DO...713.m153.l1262

http://cgi.ebay.com/PYLE-10-1000-WAT...QQcmdZViewItem

As for an amp, I would go with a 340 watt high level input unit.

http://cgi.ebay.com/JENSEN-JPA1150M-...QQcmdZViewItem

Speakers will be replaced with upgrades at stock sizes front and rear.

Any other suggestions? Is there an easy DIY for setting up an amp on the OEM deck?

Really appreciate the help!