hi all....sorry to interrupt half way tru...just wanna pour in my 1 cents..
to be honest, i believe most of us here have gone through the same path as OP, starting ICE, ask around friends which audio shops are OK, then go in ask for price, price nice, install, done, excited for the 1st time listening to the new system, listen from driver's seat, passenger seat, from back seat, then listen from outside of the car....
then start to ask friends to give comments....some say "oh nice nice shiok...", some say " ahh, too noisy...", some say "ahh? got difference arr? sorry arrr...i don't know leh...."
then one fine day, when we got a change to listen to the "REAL" thing, a proper SQ or SPL setup in other cars...we're like....

and the worst part is, the entry level for either SQ or SPL isn't actually that expensive, probably a little more then what we initially spent!

*ahhh.....i've been conned!!*
to the OP, in my humble opinion, you don't have to rush to change your whole setup. if you're really interested in ICE, or rather "sound reproduction", and willing to take this as a life long journey to pursue the ultimate set that u really like, make full use of ur current system. Make this system as your benchmark at this point of time, what u like, what u don't like, or rather, to be more direct, listen to couple of your favourite tracks, repeat it numerously....try to do active listening and compare your car system to any speaker/headset/earphone that are accessible...they may sound the same initially, but try listening a few more times.... : (these are some example that i always do....)
1) probably start with the vocal as this may be the most obvious part of the song...try to define how's the vocal like...the easy term is whether the vocal is "thick" or "thin"....with this, we can't really know speaker A sounds more accurate then Speaker B, because we doesn't know how does the singer sounds exactly in live, unless u're able to record someone's voice with a calibrated mic and play it.....the purpose of this is to try to differentiate how different speakers play vocals....the other thing with vocal u might be able to notice, given that ur recordings (CD) are good, u'll be able to listen to the singer taking his/her breathe when he starts singing, or he/she is singing with watery tongue,etc etc...sometimes, u can even hear the mic being switch on just before the singer starts singing...
2) where's the position of the vocal? can you "see" the singer sings in front of you when u close your eyes? is the position of the vocal wide spread, coming from everywhere, or u can define a single spot where the vocal comes from? Is the vocal right infront of your face, or far behind the windscreen? Is there a 2nd singer present? if so, are the 2 vocals mixed together, or u're able to spot them individually?
3) next, try to listen to the instruments in the background as well.....there might be a drum set(can u listen to the few different toms, the kick bass, the cymbals, whether the drummer just hit the hi-hat or ride cymbals, or he just stepped on the hi-hat...), guitars...electrical guitars, distortion guitars, acoustic guitars (try to differentiate nylon or steel - strings), bass guitars, and in bass guitars, try differentiate the different bass notes... , violins, piano, and the list goes on....this will be very useful if u're familiar with instruments as u'll know how that certain instrument should sound...if not, don't be despair, try to get some audiophile recording live performance, listen in your car and various different speakers, then watch the video of the performance (which means you have to look for one that have CD and DVD/youtube version). watching the video helps you to confirmed what u've heard, and what u've not heard....or even better, go to live performance, and my personal preference, jazz, try go to any jazz bar with live performance, listen to the instruments, the vocals, and the positions...
4) listen to your drivers (individual speakers), get used to how they sound, are the tweeters too bright? too mellow, or just right to your taste, how about the midrange, sounds just right, or muddy? same goes to your mid-bass... and for your sub, as u've said, its too tight, not deep enough...maybe u might wanna find some other tracks with deep bass notes, because probably, the songs that u're listening to may not have the deep bass notes, hence u're unable to listen, or rather feel them....[i personally love Pirates of the Caribbean: The Curse of the Black Pearl Original Sound Track, some of the tracks are nice and goes deep....=) ] other members might suggest a few for him too? ^^
now, after being soooo long winded about active listening, here comes the important part...
All this fine details will be useful for you in future to compare with other setups. I believe all ICErs(either SQ or SPL from all different levels) are willing to let you in to their cabin for a listening experience, and hopefully by then you'll know what u're really after, what u like, and what u dislike...
therefore, it's quite important for you to familiarise with ur current setup before jumping into other proper SQ or SPL setups because that time, u'll concentrate and find out what's soo good about this particular setup that your's are lacking, what you don't like about this setup, what components they are using (obviously, only if they don't mind to tell you...), by this, the "components" doesn't refer to the tweeter, (midrange if 3 way), mid bass, it refers to the complete set, from what headunit, what speakers, in what location, what amps, what sub and how was it setup being sealed, ported, IB, or bandpass and etc, and the size of the enclosure, what speaker cables they're using, the RCAs, any processor used, how did they cross all their speakers if it's active setup, etc etc etc...if its too much, probably focus on the speaker and amp combination because i believe that's the 2 components that will determine how the "sound" will be.
listen to as many setups (SQ or SPL) as possible, take note on the components they are using, if it happens that u're able to listen to the same speakers with different amplifier, take note the difference as well....
without a point of reference (in this case, its you who are doing active listening to your setup, hence your setup will serve as a point of reference), u'll be amazed on every single car you enter that has been properly setup without knowing what u like and dislike, and u'll be more confuse as all the components are soo good that u don't know which one to choose from.
and also to let you know ahead, every car has different acoustic properties, hence, the exact same system will not sound exactly the same in two different cars. they will only sound similar....
for the active listening part, its all about frequency response of all different speakers with different components hooked up together in different environments. If you're interested, more can be talk about this as this is a totally different topic...
I'm not a professional, i'm just a beginner in ICE and i'm after my own ideal SQ setup. Above all are not my ideas, they have been pass on to me previously by different people from different continents with the same aim: to build the ideal sound system of your own. So i'm here to share abit of my experience in searching my ideal set of ICE. if you're interested in my journey, i don't mind to share it with you....
last but not least, always remember that everyone has different opinion in their taste, u might find no one in the community that likes your taste, but not to worry, because you're the one who spent the money, so it should sound right to you, not to others. as the saying.."always trust your ears"
just my half cents....=)
*pls do correct me if i'm wrong, as i'm also a normal human that are bound to make mistakes...

Added on May 3, 2011, 1:18 ambtw, my experience may lean towards SQ setup, so alot may or may not apply for SPL...
This post has been edited by hyy87: May 3 2011, 01:18 AM