Easiest/best/cheapest way to upgrade the standard stereo?

[Ari]

I've got a Merc SLK which I love, my only criticism is the standard stereo is a bit flat sounding. I don't want to replace it as the mobile phone system runs via it, it's got an iPod dock, and it looks right in the car, but I would like to try and improve the sound.

I'm guessing a speaker upgrade might be the best way to get a useful improvement for minimum cost/hassle but no idea what would be the best way to source direct speaker replacements (don't want to have to modify the car) or what type to go for.

Any suggestions, either for speaker types or other ways to improve it, and has anyone tried this (in any car with a standard stereo) and how have you got on?

Appreciate your thoughts, thanks.

[garycat]

Get an underseat sub, something like this

http://www.caraudiodirect.co.uk/focal-access-bus-2...

That will free your door speakers from having to produce low frequencies, which can muddy the sound. You can then upgrade the door speakers with decent components and an small amp. Ignore rear speakers, they just confuse the soundstage.

[Ari]

That sounds like the sort of plan I had in mind.

Any suggestions for "hi fi" quality speakers that'll fit straight into existing slots? Are there manufacturers that do "like for like" sizes and fittings?