[konafocuswrc]

fact - bigger isn't always good for bass..
aftermarket deck will give you more output..

if you want to keep stock headunit but add aftermarket amp, then line out converter will give you rca connection..
to install, 12v, ground and t tap 2 speaker wires to rear speaker wires.

and yes, do the dampening, not only to stop rattling but it will give you better deep tight bass..