Bmw Stereo Upgrade Help!!!

I have the BMW 328I 1996 with stock headunit/6CDchanger. So far the only upgrade done is replace the rear speakers (4" with new 4"). Sounds better but not much!

What is the next best upgrade:
1. Replace headunit (but what headunit works with factory CD changer??) $200+
2. Replace OEM amp in trunk with OEM Harman Kardon AMP? $75
3. Replace OEM amp in trunk with aftermarket 6 channel amp? $200+

you should drop some subs and an amp in the trunk ^_^ i dropped 2 10' jbls about 500watts and it sounds really nice and loud

I have a 1996 320i fitted with a Kenwood Head unit, Kenwood speakers all round, 10 CD stacker in the boot and Four channel Blauplunt class A amp running the speakers.
The sound is real sharp, nice and clear etc, no distortion, but there is stuff all sound in the lowwer/deeper range. Have been talking to the audio specialist and he said I need to fit a sub in the boot ported to the car. Says that it will sound sweet if I do that.
The cars are so well sound deadened, that you loss all the bass - the reason you need to port the sub into the passenger cabin.
So planning on getting a sub fitted soon.

Cheers,
Rossco
1996 E36 320i
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