SO today im working on getting the wiring in place for the sub im installing in my 07 limited.

My question is this, are the outputs from the radio filtered, as in, do the front speakers receive full spectrum sound are the rear speakers (subs) just low pass?

Im going to tap the factory wiring pre-amplifier and piggy back those rear speaker inputs to the amp for the sub, im just wondering if I should pick up a low-pass filter or not if the signal is already filtered by the stock headunit.