Doesn't front-end heirachy apply to cars? i.e crap signal in = amplified crap signal out... so best to upgrade the front end and then cables and speakers etc etc.
I've got all the other bits and pieces too Couple of high-end Alpine V12 amps and a nice DAB / SD Blaupunkt Woodstock head unit and all cabling, if you're interested.
infinity are awesome in my experience. still got the standards in the trophy but in my previous car I had some £75 infinity components and they were awesome.
Good one Sam, the standard Trophy items are shee-ite. I've got a 7 year old 'stripped out road racer' that didn't even have a radio fitted as standard and the speakers are miles better than the Trophy ones. They start to crackle with the volume about half way, if I kept XOG I would have done this next.
Quicksilver - all audio gear is available except for Sub - I had planned to migrate them into new car but hasn't quite happened so considering making some space now...
Took me a while to fit them - I decided to remove the top of the dash in the process, turns out this step wasn't necessary in the end (you can just twist off the tweeter covers to remove the existing ones, and the kenwood tweeter holder nicely push fits into the hole), but I did take the opportunity to strategically apply some blu-tack under there which has almost completely eliminated the buzzing that it used to produce at certain speeds. That alone was worth the dash-off mission.
In terms of sound, these are a decent upgrade to the standard speakers, and were just as big a step, if not bigger, than upgrading the radio itself. Combined with a kenwood head unit, and a usb hdd, I now have quite a listenable system. It's not quite got the control, or clarity of an amped system, but it is now comfortable at reasonable listening levels. Previously there was a delicate balance between road noise, and tweeters turning symbals and other high frequency stuff into unbearable listening pain, which often resulted in the 'off' button being depressed.
The reason I chose these are that they have an adjustable tweeter level - I've set it to -2dB to help compensate for the seperation between the tweeter and woofer, and, from the spec at least (response down to 40Hz), the intention would appear to be that they don't have to be combined with a sub, unlike some of the more specialist brands. Having said that, specs are very poor way to compare products from different manufacturers, and I haven't tried any others in the clio, but these ones do seem to shift quite a bit more low frequency air than the std speakers.
If I wanted some that were quick and easy to fit (even if I'd left the dash on, there was still reasonable effort in wiring up, and hiding the crossovers) I would try the pioneer TS-Q131C (http://www.pioneer.co.uk/uk/products/25/132/201/TS-Q131C/index.html) which look to be a direct replacement, right down to using the oem speaker plugs, and unamped, could be just as much of an upgrade as the kenwoods, and are a decent amount cheaper to boot. The other option would be to avoid components in the front, instead, disconnect the tweeter, and replace the woofer with a good (eg KFC-PS1300) full range. This would avoid the sound problems caused by having the mid and the high frequencies coming from two different places. You might then need to boost the highs a little to compensate for the fact that they might not spread so well from the footwell.
Finally, don't make the mistake of spending £20 on a pair of speakers and thinking you'll get an upgrade. Unless there is something wrong with the original one's this will likely be a case of replacing like with like, or even downgrading.
Also don't believe people who say that components need a separate amp. They don't. Electrically they might even be an easier load than cheaper speakers. Of course, they won't sound their best powered by a head unit, and the point of diminishing returns will come sooner - it would be much harder to tell the difference between a £200 set of components and a £600 set without a seperate amp, but despite some advice I was given, I can confidently say that changing the speakers, without adding an amp, is a worthwhile upgrade (in a clio at least).
Hope this helps someone out there - didn't meant to blather on for so long, but I was struggling to put some coherent information together on this subject for a while.