Arny Krueger wrote:

Not quite. Harman owns both JBL & Infinity (and a ton of other brands)..
Infinity and JBL car audio speaker drivers may or may not be made in the
same Harman plant, no matter how the system is branded. Ditto for Levinson.

Ah - my bad. But they are all very simmilar. The Infinity car speakers
are the premium brand, though - much better IME than the JBL models.

They certainly sound better than the Alpine and Kenwoods from what
I have heard - but usually are too pricey for my budget - so I
usually "settle" for the Kenwoods - which sound 80% as good.

It *might* be that the goofballs at the factory put a normal
factory stereo that is meant to drive 8 or 10 ohm stock
speakers in with a set of 4 or 6 ohm Infinitys. A gross impedance
mismatch would create exactly the problem you are experiencing -
flabby, dull sound no matter what you do. I had a GM years ago
that had that problem - so I had to search a junkyard for stock
10 ohm 6*9s for the rear.($20 IIRC)

You see - they put in the stereo first sometimes and sometimes
the speakers first - then slap the other unit in, so if you get
a "upgrade" package, sometimes they weren't really tested/mated
to work well together.

I bet that a new stereo capable of driving all of the speakers
at 4 ohms will fix everything.