unless the stock radio has rca out puts that go to the amp, your not gonna have a easy time finding a amp that will connect into the current wireing setup. I'm not sure how the systems with the 6.5"'s are, but mine went directly from the speaker outs to the amp, which most aftermarket amps wont do.
also, id92, underpowering doesnt cause the subs to blow. subs blow because they over heat from too much power. and the subs wouldnt short out, the amp would. which means that the ohm load was too low for the stock amp.
good luck in your search,
Jeff aka Lamah