Going with keeping the stock head unit and adding some Focal speakers up front w/ a large Orion amp which according to the installer, will be able to run both the speakers upfront and some subs in the back. Don't know what to do about adding subs in the back. Dealer is wanting to build an enclosure for 4 subs which will take up the front portion of the trunk. Not sure if I want to lose that space and most importantly lose the benefit of the fold down seats. Not looking for any huge base response, just want a tight an accurate sound. Any suggestions?