I have a 2009 LS (AA5 option), I went down to my local car stereo shop to ask them about improving on my factory sound. The estimate to replace the factory speakers with 5.5" coxail with 075" Silk dome tweeters, add a 5 channel class D system amp., 8in sub-woofer (150W, 4ohm),2 channel line converter w/ACC, labor and other misc parts came to $2263.78, It has been along time since I messed around with car stereos, but that sounds high. Is it?

 

Depends! if your getting all this professionally installed your talking about $500 dollar installation fee. i just upgraded my speakers and i highly recommend polk audios
http://www.amazon.com/Polk-Audio-DB6...p_ob_e_title_3

they sound amazing for the price

the amplifiers are whats gonna kill you.. USE EBAY

if you take your time and find items for the right price you could do all that for half the quoted price

 

Thanks, I haven't delved into the car audio systems since my 8-track days.
Can I use he factory speakers and just get the 5/6 channel AMP installed first, do I need a sub-woofer with an AMP?

 

your biggest improvement is going to come from changing out the cheap paper factory speakers first.

If you spend money on amps and that stuff first, you are going to be very disappointed in the results you will get for the investment

 

That may or may not be overpriced, depending on the quality of work and what exactly is done.
I would replace the door speakers as you said with good 6.5" coaxials, dont need separate tweeters. That may be enough for you if you just want an improvement in sound quality. Make sure they are 2ohm to match the output of the factory system. More common 4ohm speakers may actually reduce the volume output. Its a fairly easy job (even a DIY) and shouldnt cost a lot.
If thats not loud enough, then get a 4channel amp. Note that getting an amp installed at a shop is pretty labour intensive as it involves removing the interior in order to run the wires and taking apart the dash to tap the stereo and add the line converter.
For adding a sub, if that price was to put it in a custom enclosure where the stock subwoofer should be, then it could be a decent price, again depending on quality of work done.

 

Take a look at what I did myself. It's time consuming, but not really difficult if you halfway know what you're doing.shop around , listen to what YOU like in the way of speakers.