If you simply want to add a sub to our factory systems, a simple LOC will work for you.. You would want to have an amp with a built in crossover for the sub though.. The cleansweep and the RE-q are designed more for factory systems that have odd auto EQing and things.. ours doesn't do that.. (I know my subaru factory HU does, that's long since been gone though) A simple, cheap LOC should do.. I'm not a fan of them personally, but I would recommend getting one from Navone Engineering if you do..
http://www.davidnavone.com/cart.asp?24&cat=7Everything looks basic, because it doesn't need flash to work and work well... David Navone (the manufacture) is the grandfather of car audio... lol..