[_paralyzed_]

If you turn the bass level down (0 or negative) do the stock speakers sound okay?

Usually people turn the bass up, and door speakers just physically are not large enough to produce good bass, so the sound distorts and the highs are effected because they are coming out of the same speaker.

Even the best door speakers won't produce much bass, again, they are too small.

I would start with a 8" or 10" sub. (powered is easiest, they are cheap on ebay)

Turn down the bass on the radio so the front speakers are only playing mids and highs (what they were designed for) and use the level control on the amp or powered sub to set the correct bass level.

Any aftermarket door speakers will be way way waaaay better than the stock units, but you mentioned wanting bass, and you just can't get any decent bass without a subwoofer.

Also, rear speakers won't help you in the drivers seat at all. Rear speakers are for rear passengers. You'd be best off getting a sub, then if the highs still aren't enough replace the front speakers.

Stock speakers can usually play quite loud if you don't send bass to them. Better yet, if your deck has crossovers use them and completely eliminate any bass information from going to the speakers.

Subs are for bass. Bass needs subs.