Originally Posted by VXNIT
In my opinion you are not going to get "tremendous bass" out of any pair of 6.5's
as far as your deck is concerned, if its stock it has a very limited amout of power. the stock paper speakers didnt need alot of power to move them.
most new decks push around 50 watts a channel max. thats about 25watts rms *4. if you want to get amps you need a deck with rca outputs. the cheaper ones have front and sub outputs at around 2 volts. the nicer head units have front/rear/sub outputs, and the voltage goes up depending on the model. with amplifiers the higher the voltage through the rca's the more efficient the amp can operate.
you will notice a difference in sound just from upgrading the deck. start there with better speakers. and see if you like it,... if you dont you can always add an amp to the speakers later.
as far as the sub goes. a 8-10" woofer will add alot of sound to the car in the same way your woofer in your home does on a dolby 5.1 sysem. alot of companies make a self contained woofer/box/amp. thats relativly easy to install, and they add a nice touch to the sound in a car. infinity has a basslink system that Ive heard before. its not bad for the money. the sub will also play a lower Frequency than the coax will play.