If I am driving seriously then I don't have the radio on, or just TA's.

In traffic or cruising on the motorway then I tend to listen to stuff as a
background, but not devote serious attention to it as I might when at home.

A hi-fi consists of three sections: -

The source
The amp
The speakers

To a first approximation "the amp" was sorted in the early seventies when
low noise high fidelity transistor amplifiers became common.

To a first approximation "the source" was sorted in the mid eighties* when
CD's came out.

Speakers remain the main obstacle to decent listening.  In a house only the
space available and your budget represent an obstacle to having good
speakers, but in a car there are serious space constraints, the cabin is not
ideal for listening (both front seats are off centre for a start) and
usually the maker has fitted some (and a combined TV/radio/GPS/computer)
already.  This makes replacing the factory fit with anything significantly
better both messy and very expensive.  I normally listen to my home stereo
on "direct", but in the car it is probably cheaper to fiddle with the tone,
fade and balance controls to get the setup you want rather spend $$$$ on a
setup up that is unlikely to produce significantly different results.  I
suppose you can get better base if you use the entire boot as a resonant
cavity...

* when CD's first came out I could easily tell whether an FM radio station
was playing a CD or vinyl (on its very expensive decks) while driving at
??mph in a 735iSE on the M6.  This was despite FM transmission, a fairly
plain radio, road noise and IIRC factory speakers!

You guys slay me - what do you really buy a "car" for?

If I want to listen to "sounds" I buy a hi-fi set up and sit at home in comfort
to hear and digest what I am listening to.

In a "car" you get all the traffic noise - passengers talking (unless it "show
off time" and " look and listen to what I have") and then there is the
distraction to you - the driver - and CRASH you wipe out some poor soul that
only went to the supermarket for lunch....

Buy a car and drive it Buy a sound system and sit at home listening to it.

standard sound in the e46 is total crap...I had one
hk sound in the e46 is very very nice, but I can't say perfect... I have
one actually...
(it comes from the bass that are "gloudy" ? because the subs are at the
back and too isolated from the cabin. you can't really enhance the other
speakers...
but I read some article (dont remember where) saying that to really
enhance the hk sound system you would have to pay some $5000... and
rethink where the speakers are located...
so I dont think your $100 system is even worth the try...
(it would have been if you had the standard x5 sound system...)

Thank you all for your help.

To answer some of your questions:
1] Typo (sorry) - "Bostons" should be "Boston" or "Boston Accoustics".
2] I didn't know that the 10-speaker system is a HK system. I'm familiar
with the crisp clear Bostons Accoustics sound systems. No, I haven't
listened to the sound in the car yet. It's been purchased at A BMW dealer
with the help of a friend of mine who has his own non-BMW shop. The sound
in my E46 is worthless.
3] The X5 will be shipped to the Netherlands in Europe and was wondering
how much it would cost to replace the speakers in the US and over here in
Europe.
4] Just found out that "Crutchfield" recommends the S55 and SX55 for the
X5.After Price break/rebate the SX55 would cost me $99.99.

Hi all,

I have purchased an E53 X5 (2005) which will be delivered next week. It has
a 10-speaker HiFi system but would like to replace these with "Boston
speakers".

My questions are:
1] Does anyone know which Bostons speakers will fit
2] Any idea how much this will cost

Thank you for your help.
Sonny