ok im getting ready to install some subs and i want to keep the stock head unit and im gonna get an rca adapter for that but i was wondering what do u have to do to remove the stock head unit

http://www.scionlife.com/forums/viewtopic.php?p=174308&highlight=grommet+amp#174308

here is a good guide on installing and amp to the stock unit.

Why remove the HU? Just tap into the rear speaker wires and run them directly into the amp.