Stock radio + Subwoofer?

Is it possible? and is it worth it?  I got this http://www.lightningaudio.com/products/product_details.asp?cat_id=1&series_id=6&family_id=16&item_id=90717&locale=en_US and was trying to see if i could do it or not

that link does not work. But you can add a sub and amp to a stock radio by either getting an amp that has speaker level inputs, or by purchasing a Line Output Convertor. You will have to tap off the rear speakers to accomplish this task. Very easy to do, just takes a little work. You will still need power, ground and remote turn on for the amp to work.  

to answer your first question......what hillbillyinOhio said above^^^ is correct, and to answer your second question.....it depends on whether or not you want to spend the extra $100 or more for an aftermarket radio right now...if you got the money and you want to spend it right now then go ahead and get one, but if not, you can just hook it up like it was mentioned above and get the aftermarket radio later, thats what i did and im happy with the result

well i fixed the link .  would i need to tap both rears? or just 1 

I personally think it is better to tap into the front door speakers because they get the most bass signal. Or so I have been told... 
 
you'll need to tap both, b/c of the use of the balance control, for example, if you tap into the left and balance it to the right, you lose bass. Balancing to the left will cause too much bass and not enough treble.

saw the link, i could probably get you a better quality setup for about the same price, if you are interested.  Any bass that you can add to a factory system will be a big improvement.

if  i throw my old battery in the trunk would that be enough to run the amp? or am i looking fr a easy way out lol

that will not work, unless you wire it up inline with battery in the front and alt.  gng to have to break down and ge the amp install kit. there is a grommet on pass side firewall, you can run power wire though there. for the ground, underneath drivers rear seat.

i got it for 75

and thanks hillbilly ill look tomorrow was raining today.
also if i undo the battery wil i have ti get the radio unlocked or something?