Cool Bass Upgrade

[savoir-faire]

I got everything installed, but the subwoofer is giving poor response. I think it may be because I tapped the rear speaker wires for the inputs. Does anyone know whether the rears are supplied only high frequencies? In otherwords, is there a crossover at the amp?

If this is the case, does anyone have experience with tapping the door speakers? I assume those are fed with lower frequencies. Is it possible to easily find these wires in the main cabin? Even better, does anyone know whether it is possible to get left and right RCA type feeds from the factory head unit?

Thanks in advance if you can assist.