Upgrade the factory audio

Simply from what I've observed when it comes to car audio (not stating anything as "facts"...just my opinions)...I don't believe replacing the speakers will make things sound any better. If you get aftermarket speakers, you'll need a powerful amp(s) to power them to their full potential. Head units alone cannot channel that much power. Also, from what I've witnessed, people who hook up amps to factory head units often experience a whining noises coming from the speakers (the alternator) or a loud popping sound when power is turned off.
So, I'm still contemplating on whether or not to upgrade by putting in an amp and sub. Plus, the space in the back looks too small even to fit a 10" sub (and cover it with that...whatever its called--the thing you cover to hide inside your trunk). You won't get much "thump" without a big enclosure for the sub, and a typical ported subwoofer box looks like it would take up the whole trunk space.

Other solutions? I am currently looking into the Infiniti Basslink as an option.

When it comes to simply installing car audio (amp, for example), I'd recommend DIY. It's really not as difficult as people imagine. However, if you don't want to go through that labor, I'd at least recommend knowing enough to let the shop people know where exactly you want the amplifier placed and how you want wires routed. Prepare for a debate, though. They'll make any argument they can to make their labor as easy as possible.
In my experience, "professional" car audio installation is a coin toss. I've seen people bring back a complete mess in their audio setup, and some very impressive. If I were to visit a shop, I'd ask them to show me samples of their work (looking for neatness), ask about how many holes they're going to cut into the carpet, ...and (especially) about possible side effects (the loud popping noises and/or whining noises from the alternator I mentioned in my earlier post).

Alot of work, it took me and my buddy about 30 hours. Im running Hertz Hi-Energy Components 2 way up front. Infinity Reference Coaxils for rear fill in the rear doors. Alpine Type R 10inch in a 1.25 Cubic Feet Sealed box, with the front doors dynamatted and the Rear hatch and trunk area. As for my amp, I went with the JL Audio 900/5 (5 ch amp, with 110RMS at the four each of the 4 channels and 1 500RMS mono for the sub) which was installed under the front passenger seat. We tried without a headunit and its just not good. Speakers wont play as they should as well as the sub. Basically stock head units are equalised to make stock speakers sound good, in turn this equalisation is a mess for any aftermarket setup and there will always be noise from the stock radio, constant buzzing. I can only imagine how this stock radio is tuned to run BAMBOO speakers lol.

For anyone who still wants control of the factory radio and still wants good sound, there are solutions like the JL Audio Cleansweep, which basically brings the signal for the stock head unit to a FLAT responce so you speakers/sub sound the way they should from the factory. there after any tuning is done with the Cleansweep and you still have your factory radio working, this however is still not as good as having an aftermarket headunit. However there are always setbacks when using a cleansweep which I wont go into detail about. I however always believed in Headunits, so we custom fit my Pioneer 8300 into the center armrest (alot of cutting and dremeling, so be aware, the center console must completely come out and they are metal shields that need to be tampered with and cut). My armsrest closes as it should and I know that I have all the tuning I need from my amp and speakers that I spent alot of money on here in Canada. I didn't spend alot of money for nothing, so I figured I would go all the way or go home LOL. However my stock radio no longer works and as of now the module which supports bluetooth for an aftermarket radio in th Ct200h is still being developed. So in turn you loose bluetooth/am/fm/satellite radio from the stock radio. Since I am an audiophile I could care less, because now my system sounds the way I want it to CRAZY mind blowing as one of the members from DIYMOBILEAUDIO said. All about sound quality for me, Function over Form. I am in Montreal, so of anyone ever wanted to meet up I would be happy to show the work I've done with my buddy, so anybody interested can hear for themselves and make the push if it interest them. I have also taken enough photos which I'll post of to show you guys. Enjoy!! I was suppose to also take photos of the LED Interior or aftermarket HID kit which I still havent got around to doing, but I assure you I will this week. I have been soo busy with my audio project.

I posted a thread on here about replacing the stock sub. I've done the big time full switch out of stock audio components before but IMO the CT doesn't need it! This car has 2 stock amps which push the system pretty good.

There is one major flaw that I will say that has me pondering though I have to say I've had the same thing happen even with expensive after market parts. I'm speaking about the difference in sound quality from normal radio, sat radio, cd, and iPod. So far the normal radio and the cd are producing the best sound from the stock head unit. Annoying yes but to swap out and put in a aftermarket head unit after I just dropped an extra $3,500 for nav and premium sound....um no thanks!

The kicker sub I added ( only a 6.5" by the way with a 200 watt amp ) really was the missing link IMO with the stereo system. The bamboo speakers are surprisingly good! Again from a sustainable perspective which is a partial reason I bought this car I think 90% of CT owners won't need to upgrade the highs and mids on this car.

I have the detailed electrical schematics for the CT from the dealer and any changes of more than 350 watts on this car I would strongly consider adding an additional small battery to run your additional amplifiers or head unit. Another solution would be looking into purchasing an after market alternator that can crank out more juice to keep the factory ion battery from not getting to depleted . Anything under that wattage above and your not compromising the cars electrical performance.

Haven't had any problems with my battery depleting any faster than normal with anything under 1000rms on any of the vehicules I've owned keeping a stock alternator. Hence now my JL is a 5ch 900watt and my gas consumption on average went down by 0.2-0.3 L/100km which for me isn't drastic. Secondly the vehicule doesn't run any more than it should. My techs at Lexus where I work did full electrical system amp draws and its still within normal range, so I am very happy about that I started with adding a kicker cvt 10inch with a small amp and it just wasnt enough, I was just hiding the fact that I wasn't a happy camper.As an audiophile and coming from a previous Focal and Boston setup, stock just didn't do it for me. Having a quality 10inch in a propery sealed enclosure is more than enough for this hatchback with no rattles and enough to vibrate your hair if need be, all without detering the quality of the front stage I live by my USB key with either 320kbps or AAC in my 32 gig patriot with all the music I could want. Then again like I said to each his own, no one can challenge another person ears But its about 2 weeks and counting with my audio system pumping everyday and I'm still getting an average of 690-750km on a tank . I love this car!!!