Factory amp connector adapter?
 

Here's a thought that I haven't seen before. Maybe someone mentioned it, but I haven't seen it yet.

I believe the factor unit for the BRZ (not sure about FRS), runs a full spectrum signal to the trunk, where the factory amp sits. The amp then filters the input, and sends a low pass signal to the front door woofers. Is this correct?

My though for a simple/easy/unobtrusive audio upgrade is simply replace stock amp w/ a small 2ch amp around 50wx2 utilizing factory wiring, and upgrading the front door speakers to a set of full range 2-ways.

The main "problem" here of course, would be finding a 2ch amp that would fit in the stock amp location, and an adapter to utilize the stock amp connectors w/o splicing up the factory wires.

Anyone know if this is possible and where to get these adapters?

+1 on this, I would love to do this instead of opting for the OEM Audio+ option.

http://www.ft86club.com/forums/showthread.php?t=42239
Ktp-445u is bridgable into 2 ch.