I just got an '07 GT with the Monsoon audio. However since it doesn't have Bluetooth I'm going to be swapping in the Pioneer I currently have in my Subaru Impreza (Minnesota hands free law). Is it with tracking down factory rear speakers? Both are missing. Or should I just budget bypassing the stock and replacing all the speakers? Even the $50 Sony or Pioneer I can buy at Walmart are good enough for me (messed up ears due to lots of was infections as a kid).