Re: Speakers
Quite a lot of how good a speaker sounds depends on the installation. A good speaker installed badly will sound better than a bad speaker installed badly, but the same bad speaker installed well may sound better than the good speaker...
The basic rule is an 'infinite baffle' configuration being the best to strive for. This means having the speaker installed in a flat panel (baffle) with the sides extending forever in all directions.
Obviously this isn't possible, but the closest approximation is to have the speaker sealed in a large box. The best way to achieve this (within the confines of a car door) is to seal off all the holes in the door's metalwork using self-adhesive bitumen sheet (you can use other materials, such as 3mm MDF).
Most people use the bitumen sheet to deaden the door outer skin, which is OK but a separate issue again (and almost all cars already have some deadening installed for the outer skin to give a nice sound when closing the door, though you may wish to improve on it).
I remember coming up with the door-sealing idea by myself (did it to the front doors of my Alfa 164 when installing Infinity Kappa 6.5" speakers) but I recently read about it on
http://www.caraudioaustralia.com/content.php?contentID=19
Note that my technique was slightly different (I used the bitumen sheet to cover the holes) but the theory and result are the same. I did a comparison test between one side (standard) and the other side (boxed-in) and the difference was surprising. One day I might do it to my Stilo, as the sound isn't particularly great... There's enough bass to feel, and quite a bit of crackly treble, but not much in between. Perhaps in the Stilo the sound is below the average new-car standard?
Usually standard-audio is carefully chosen to give maximum sound for the price, and you usually notice that aftermarket speakers are a little quieter and flat-sounding due to having less efficiency (best speakers or old paper-cone speakers are over 90dB/m, cheap speakers more like 87dB/m). You'll probably end up spending upwards of 60 pounds/pair to get speakers that sound any better than standard. Cone rigidity and magnet weight are both important, in my opinion... Careful you don't end up with inaccurate, 'booming' bass as well, that's easy to do (put in a 15" sub...
)
-Alex