You dont have to settle for garbage sound or a trunk that bounces & shakes with the beat,great sounding & very loud car audio can be done but it takes time, trial & error & cash.
I just finished a 5 month install in my mustang,something i had to come to grips with was that an automobile is a very different enviroment than a home,your worst enemy in making a great car audio system is road noise,elimenating outside noise is a must.
I ended up pulling all the interior panels,door,rear seats,carpet around inner firewall & at the inner trunk panels & trunk carpeting,i then filled all holes in the sheet metal with spray foam,after sealing all the holes i installed a layer of dynamat sound proofing & reinstalled all the panels & carpeting,in the trunk i used 2 layers of dynamat before putting the side panels & carpeting back in,dont forget to install dynamat around the blinker housings & the inner trunk lid.
Sub's & sub enclosures are of next importance,having high spl's & having quality sound do not go hand in hand cheaply in car audio,the enclosure plays a huge role,i got tired of trying to find an off the shelf enclosure that would sound good & still produce high spl's,i ended up having a high end car audio shop make & tune a specific enclosure for my trunk,it was worth every penny($450 just for the box,no subs).
I then found out was that when choosing subs i needed to find subs that could sound good in sealed enclosures & capable of high spl's while they were running in 4 ohms,running 2 ohm or 1 ohm subs sounded like crap plus added problems with being able to send enough constant power to the amps,JL Audio is the only way to go for great sounding subs,nothing else compares.
Amplification,this is a spot where the "all properly designed amps sound the same" falls flat on its face quickly,for worthy amps you need to look at manufacturers like Zapco,Mcintosh,Soundstream,PPI & US Amps,mass market amps like Clarion,Mtx,Lightning Audio & Rockford Fosgate wont cut the mustard,anything that best buy or circuty sells in their car audio depts is also junk & wont cut it.
Powering your amps,most factory alternators are not capable of producing enough juice to power your amps properly,this is also a spot where the "power is power" line of thought will not apply,installing capacitors to store power will only help slightly,i ended up going with a 250 amp ambulance alternator but a 200 amp model should handel most amps easily.
Body ground is also important,your amps will need to be grounded in 2 spots each,one spot to the body & one spot to the frame.
Head units,as long as your running a decent quality head unit with atleast 15 watts & that has 2 sub outs & a rear out you'll be fine,keep in mind that with super expensive head units most dollars spent go to pay for the gimmicks like color tv screens & extra features like 5.1 that wont help your sound.
For about $1,500 you can update your current system to the point where it sounds excellent,for around $2,500 you can put together a world class car rig that will blow away the kids syatems & still sound great but keep in mind that you will never end up with a system that has pin point imaging,in car audio imaging is impossible,if don right you can have a system that is very dynamic sounding,not boomy or bright & a dead quiet background.
