Is it just a one-way speaker? How much improvement do you think I'll get with a 2 or 3 way speaker?

 

Yes, it is just a single cone speaker. That's probably why they originally designed the OEM system with the EQ. The single cone speakers need a huge boost to the mid and high frequency range to even sound decent.

I just replaced my front stock speakers with an old pair of Boston Acoustic Pro Series 6.2 (2-way component). I put the tweeters attached to the rear view mirror sail panels. (Seat memory switch takes up the perfect position for the tweeters.) The high frequencies were so over boosted, I has to bypass the EQ the next day. Just for kicks, I put in a temporary DPDT switch to pass/bypass the EQ. I also set it up so that in the bypass mode, the HU signal still flows into the EQ so the subwoofer output isn't effected by the fader.

The front soundstage sound is much smoother with the EQ bypassed. Back speakers sound really dull now and i need to replace those also. Probably going to replace the back speakers with simple 2-way coaxials (Boston Acoustics RX67).

Here's the biggest drawback so far. Now that the EQ is bypassed, the volume level output is about two-thirds what it once was. The sub output level is a bit to high now (unbalanced). I think i'll need to add an amp now to get the volume level that I like. I was thinking of picking off the line level signals from the HU to feed the amps. I know I'll lose the fader control, but i never fade between the front and back anyways.

-- pierre