I think you're kind of missing the fact that you are going to have a VERY hard time drowning out your voice with bass (unless you get to an extreme competition level, but we won't go there). Your voice is in a range about 500-5,000 Hz (I said about) usually. Bass is nowhere near that. You need to get rid of your stock speakers and get some good coaxes or comps, and amp them. I just really think that if you get new speakers the amount of volume you hear will be much much louder.
Speakers I would recommend are Pioneer Revs or PG RSDs (insane midbass for price).
Does anyone agree with me?