I put this behind my rear seat. It is excellent. Don't listen to the people who say that powered subs are crap, they think that they all sound like Bazooka Tubes, but the Infinity Basslink is incredible.
The stock stereo should be able to be wired, but you'll be happier with an inexpensive 50w x 4 head unit. My Pioneer is old, but is great. The new ones look to be even better.