[krs03]

From what i have read the rear speakers only get a high end signal and not much power, so upgrading them has generally not added much, especially given the work involved. Just what I have read, so I didn't upgrade mine. Others will have more experience with replacing the rears.
If you add an amp to drive the rear's this would solve the problem though.

This is what I have heard aswell but according to @Koalaboy he can hear the difference, which is all I want, a more front and rear sound stage sound system. If i can get just some sound from them I would think it's worth it. Currently zero sound can be heard from the little tiny pee shooter rear speakers currently in my car.

 

[Danmac]

The headunit and its undisclosed EQ tweaks to various channels pretty much ruins any good options. You would really need to start from scratch to execute good audio in this car and even then it's a noisy beast so not much point.
It seems pretty complex to get a line level feed and even then, the head unit is a bad source with a bad DAC.

I was going to go hard on an audio upgrade but have seen the light and will do the following.

Morel Maximo Ultra 602 HE - good sensitivity to work with weak head unit amp. Paper cones so not too bright.
Door treatments - good dampening, sealing rings for mid woofers front and back and acoustic foam where needed.
USB FLAC feed when I require a good source music.

Anything more than this is diminishing returns. The rears are a waste of time. A 3-way front SQ set up would be nice, however you would need a good DSP amp to split the front L R signal into Woofer, Mid, Tweeter L and R. Plus new wiring for all speakers, plus power cables and install space. Don't think it is worth it. Still a relatively noisy car with lots of glass.

 

[Boss HOGG]

I got told that a 3way crossover or something is needed to convert the one-way in to separate the frequency from the speaker.

 

[Danmac]

I got told that a 3way crossover or something is needed to convert the one-way in to separate the frequency from the speaker.

That where a DSP would come in. it would split the L and R signal into 3xL and 3xR

 

[BRZ or DBZ]

How would one integrate a sub & amp into this mix?