Speakers sound weak

You need a crossover on those tweeters or they will sound like ass and break.  Fantastic way to ruin new stuff.  Similarly, the cone on the 'regular speaker' will not sound good without a crossover.  Why are you running them in parallel?  Try switching the polarity, maybe the wires are wrong. 

Are the front speakers real honest to god components with a crossover for the woofer and the tweeter or are they make believe wanna be's with a full range woofer and a tweeter wired in parallel to the woofer (usually with a cap on the + lead to the tweeter - thus a tweeter only crossover). To me this is two issues. The possible out of phase issue that Rushman touched on.

Fade the speakers all the way to the front. Disconnect the leads from one of the door woofers. If the bass response goes up, the woofer was wired out of phase, meaning one of the two woofers was wired + to -. Play with the speaker wires that are disconnected right now and connect them + to - and - to + and listen to both speakers. Now reverse those leads and wire them back to normal. Play the same song over and over again while you listen to the speakers. Eventually you will hear out of phase in the blink of an eye. Listen for a lack of bass response one way over the other.

The second issue that you have is efficiency. Coax speakers (which I assume are your rear speakers) are highly efficient, component speakers are not. Thus a component speaker needs that much more power to play as loud as the more efficient speakers. If you have to adjust the fader almost all the way forward to compensate for the overpowering rear speakers, this is a good indication of a inefficient speaker. The answer here is to amplify those puppies.