Okay, so I have an update. My new audio system is complete, new deck as well as all the speakers installed including the new Sub. This has made a HUGE difference in sound quality and was VERY easy to do. I wanted to share a few tips that may help others in the future:
1. If you know nothing about audio systems and just want an upgrade to your stock system, the above (earlier post) components work great together and can be had for under $400.
If you are anywhere near handy with basic tools, you can install this yourself easily. This was my first install and it went flawlessly.
2. The Kicker 2 ohm sub is a vast improvement over the stock unit using the stock amp. Only use two of the four wires that the stock sub used. I suggest using the black and red as these are the colors on the sub connectors and match up red to red and black to black.
3. For those of us with the stock 7 speaker system, there is no support beam that needs to be trimmed to fit the 5.25" speakers in the front dash. Using the adapter plate ( I used Nalin's) it bolts right up easy as pie.
4. If you have a 2004 (and likely others) with the 7 speaker system and you want to use speaker adapters to connect your new speakers (to retain the stock connection) the adapter that fits both the dash and the sound pods it is the Metra 72-6514 Adapter. These are readily available on amazon.com or at your local Best Buy store (it doesn't say they have them online, but if they install audio systems at your local store, they likely have them.)
5. Polyfill all areas. I polyfilled the dash, sound pods, and sub enclosure.
6. I chose the Polk DB521 for my sound pods. They sound great and allow me to have a great seal behind the speaker. They also allow the Polk speaker cover to be mounted in the stock position and looks very clean. I don't know how much benefit I would see with the larger speaker, but the ease of install and the clean looks leaves me very happy with this choice.
If anyone has any questions, I'm happy to help.