So you want to upgrade the factory system for better sound quality and higher volume levels... In order to get started we need a system plan. Things to consider are how long you intend to keep the vehicle, how much space do you want to use up in the vehicle and do you just want to hit a narrow band or do you want smooth system responce that will make the music come alive. Over the years I have built sealed, bandpass, and ported enclosures and changed subwoofers and enclosures often as I tried to find the right sound for my tastes. I wanted something that hit hard and shakes asphalt too but have always been told you got to do one or the other. You can't get the best of both worlds. I beg to differ.

The first thing I feel that is very important is do you own the car or are you leasing it. Minor modification of your own vehicle can produce some exceptional results but for those of who lease a vehicle modifications may not be a viable option. For those of you who cannot make any modifications unfortunately you will have to make sacrifices of space, lots of money, and wasted install time when it comes time to remove your system. For you people I will tell you there are a few different power hungry subs out there that require small enclosures that do well in sealed or ported applications. Since this is an area many people have already covered I will say anything more than JL AUDIO 13.5W7 & JL Audio 1000/1. If you can afford these and are willing to make the sacrifice of the small space required by the recommended JL Audio ported enclosure built to exact specification then you will have someting almost as good as my inexpensive suggestion below.

Now that we have eliminated those who cannot make any modifications from the reading we will look at something the Subwoofer manufactures do not want the consumer to know. Power Handling is only a thermal limit. Power requirement is important. An ideal sub would make maximum excursion at 10 watts and place very little strain on our charging system. Unfortunately if you want to hit hard and shake asphalt you're going to need to move lots of air! 10's with an xmax of 40mm cannot move the same air as a single 15... and thus will lack low end extention found with the 15 with an effective excursion of just 7MM. It's just a fact. So how can we move this air with little power and havethe fast response of a 10" subwoofer and cover all of the bass with no peaks or dips in the sub bass frequencies? A sealed box produces the flatest curve and the ported box will increase above the port tune frequency. I could spend hours coing over enclosures but the guy with no trunk is the only person I would help here and there are lots of articles already about enclosure design.

Now that we have eliminated the guy who cannot modify and the guy with no trunk lets focus on how the subwoofer works. The sound wave coming off of the front are the exact same as those coming from the rear. Our Subwoofer manufactures try to keep things simple for you and build subs to go into little boxes that just sound horrible! You put it in you yank it out and try something different and after 10 years of this you'll think to yourself there is no making me happy and I'll never find what I am looking for. WRONG! Forget what the manufactures say, period. Forget what your buddy says about how bad his 10"s are. Go look in your trunk and figure out where you can place 2 15" subwoofers without an enclosure! Now that you see where they will fit you have to mount them there and seal the front sound waves from the rear soundwave and keep them securely in place. I had room in my read deck. The first thing I did was remove my rear seat and deck trim and all of the trim in my trunk. I then covered all of the openings and metal  behind the rear seat and on the top of the rear deck with sound deadener including the rear deck except for the holes where my 6X9s once were. I used multiple layers of the thin stuff becuase it is easy to work with, multiple layed increase effectiveness exponentially and it just makes an air tight seal easier to accomplish when you seal all of the overlaping material with more material! Make sure you use something that has no odor... There are lots of good materials here on ebay. The cheapest good stuff will probably do all you need but beware many of the sellers do not offer any customer care so try emailing the seller and asking some questions before you buy the item now! You will need about 100sq feet to do this right of the 45mil grade sound deadener and that will cost less than most enclosures!

Next seal the back side of the metal where the seat is monted and the bottom of the rear deck the same way. You can contiue adding the materail everywhere the is covered by the trim of your trunk including the trunk floor. I also deadened all of the gadgets monted on the rear of the seats as well. If you are planing to install aftermarket alarms and stuff this is usually mnter there so it is best to do that before you seal it all up air tight! Also not the mounting location for you fuel pump in many cars. I sealed mine and marked it with an X so I know where it is later if I ever need to peel off the sound deadener to replace it. Now that this is all sealed (AIR TIGHT - DO NOT SKIMP HERE) we need to mount our subwoofers.  I chose to reinforce the rear deck and assit with the sealing of the front of the sub from the rear by using a piece of 3/4 MDF cut to fit close enough that it would trim out nicely. I cut the holes right where the openings for the 6X9s were to allow the subs to fire into the cabin of my car. I also had to cut out a notch for my trunk light and move the wire from under the MDF so it could be remounted on the MDF as it was on the metal before. Once I got it all cut out just right. I got a cement block to set my car jack on and jacked it up to within 1 /12 inch of the rear deck. I slid the MDF on top and jack it up to hold the MDF in place while I drilled my firtt holes to secure it. I used 1/4 X 3' bolts and nuts with large flat washers to add strenght to the monting locations. Once I had 4 bolts in I lower the jack and put 4 more in closest to the seat metal on the rear deck. I also placed one dead center and just snugged everything up to hold it in place. I also used the 2" weather strip foan on the entire piece of MDF so any contact locations would not rattle. I then filled all gaps with Great Stuff Expanding foam. Once all this was dry and hardened I then used more sounde dedener and sealed the MDF to the rear deck so no air could excape from front to rear (REMEMBER AIR TIGHT). Once that was done I marked the monting locations of my subs on the new baffle I installed and then used the jack to hold it up while I intalled the first few screws to support the sub. I did the same thing with the other one then climbed into the trunk and installed the rest of my screws.

The next step is to put everything back together and hook up your amplifiers. I hope you thought about running them first and sealeing them air tight because mine were already installed from a previous installation of 2 13.5 JL Audio w7s. If not you'll need to make holes and seal them up after. Now that everything is installed you can tune the system prior to mounting your amps and other eqipment. Once you are happy with the the settings remove everthing but the subs and wires and lay out a beauty board and place everything where it looks good on the board. Drill the mounting holes and the holes for the wires. I went to the junk yard and got factory carpet to match perfectly then covered the board with it pulled all the wires through mounted everything to the board then monted the board as the original trim was once mounted.  My board was flexible so I did not have to remove the subs to install it and I used the factory heavy grip velcro to secure it in place just like they did from the factory.

Results:

 I removed 2 JL Audio 13.5 W7s and 1 JL Audio 1000/1 amplifier from my system and replace the subs with (don't laught until you hear how my installation actually sounds) 2 15" Kicker Comps. I bought them for $178 shipped right here on ebay! After I tuned my system I went to Sound Advice and told the guy who installed my 13.5 W7s that I had made some adjustments to the system settings. I sat in the car and told me how impressed he was from the improvements that I had made to his settings and he asked me how I did it? I then said well I chunked that beast of a box you put in my trunk and I um just letting my speakers fire in the air now. This is funny, because he did not believe that I was hitting harder , dropping lower and was getting such a well rounded sound without a box but he was swearing those JL 13.5 W7 he talked me into were awesome subs and that was why my system sounded so good. Since he didn't believe me when I told him the box was tossed I had to show him. I popped the trunk and he said OH, My God! Where are your subs? I said sqaut down and look under there! He's like, man I never saw anything like that before... Why doesn't everybody install their subs like that? My answer was: If everybody installed there subs like that you wouldn't be selling any subs... I said those aren't the JLs you sold me... He looked again and said oh, what kind of subs are those? I want to get a paid of them and do this to my car... I said 15" Kicker Comps. He said, yeah the CVRs are pretty good. I said not CVRs man just cheap Kicker Comps. He had to look again, and sho nuff they were Kicker Comps. I'm not showing any disrespect for JL Audio here at all. I still am using my 300/4 (bridged for highs) and the 1000/1 to power the Kicker Comps (although the Kickers are rated 250W RMS each they are in free air and they seem to be doing very well with 1000 watts unclipped and undistorted power). The think I don't have is a Power Wedge or any box and what I do have is my trunk and the best wounding subwoofer install I have ever owned in any vehicle period with 20 years of box building and driver trial and error.

Summary:

A good Amplifier like the JL 1000/1 with all of the nifty Q adjustments, crossovers, and Subsonic Filter coupled with a Infinite Baffled Subwoofer hits every bass note without dips or peaks at an incredible level that will seem louder to the ear and can be felt more in the body than any pair of 12s I have ever heard period! The speed and accuracy of the subwoofer in this type of installaion will fool you into thinking you are running 10's, 12's and 15's because it hits hard, missing nothing and drops the bottom to shake the asphault! I understand the Folks at Image Dynamics make great subwoofer for this type of installation too. Probably sound better than the Comps but I can tell you that I am in no hurry to try them out because these 2 Comps in this installation are the first subs I have every been completely satisfied with and have no desires to upgrade now. Next Time I'll use the ID subs because I will want to see...  Last but not least, actually the most, I thank the Folks at USD Audio for placing good information on there simple website. I heard one day back in the 1980s that there were these things called Waveguides that sounded awesome but I never owned any until I found a set at a steel price of $275 right here on ebay brand new in the box. I understand now these would have cost me $1500+ new and I'll tell you what, they are worth every penny! I've used all the Tweets out there and was never happy with any of my front stage installs prior to the Waveguides. Once I heard them I had to find out more and USD Audio was talking about Aperiodic Membrane enclosures which are just an acoustic dampening baffle to controll excursion and it was this idea that prompted me into the Infinite Baffle install. With a 18Hz Subsonic filter, excursion overdrive does not seem to be an issue at all with the Comps which are designed to do this install. Couped with a 55Hz 2db boost Qed @ 1.6 all from the JL 1000/1 I have a subwoofer install that is equally impressive as the Waveguides. Thank you, Stillwater Designs for an inexpensive and impressive subwoofer and 30 band EQ! Thank you, JL Audio for an awesome 1000/1 amplifier that smoked my Polk SR 12s rated at 750 RMS each and lived to be adjusted to prived all the tuning and power to make the most out of an inexpensive Subwoofer without killing my alternator the first week it was installed. Thank you, Optima for a great battery that has never let me down... Thank you Knuconcepts here on ebay selling fine installation products such as the compression fitting fuse and ground distribution blocks, and quality power, speaker and interconnect wires. And Last but not least by any means, thank you USD Audio for making the best mids and highs I have ever heard in any car in 20+ years of doing this and for the great advice on your simple website the led to me trying something different! The question was, why isn't everybody doing this? Because everybody is not as smart as the guys at USD Audio who first though of placing the tweets in the floors and really did there homework to make major changes to the competion world of car audio sound quality. And did I way they were loud too and they handle more power than rated without blowing up! Great job all of you! Maybe this article will reach others like me who want more than just average performance!

Peace to all except when I am driving down your block! Oh, and if you are a basher of infinate baffle that is because you never heard one done right! The above is the correct or at least a good performing installation. Correct is always what sounds good to you! Just remember when your thumping in you car and a guy pulls up next to you, and makes you shrink down in your seat in embarasment do to the lack of definition, responce and clarity of your system and he's doing it at 3x the level the system you thought sounded good before he pulled up next you, that I am that guy. My guide here is to allow the entry level user to save thousands and thousands of dollars on trial an error mistakes that I made over 20 years in car audio. All of the equipment I have pointed out is either exceptional in quality or exceptional in quality & value. Don't Forget the Alpine Head Units with Bass Engine Pros that offers time alignment features and a friendly 7 band EQ from the drivers seat as well as nice crossovers and great sound quality! I've had more expensive Head units that were better with lots of extra Eqs and all but Bang For the Buck. $125 on ebay go me a nice Alpine with Bass Engine Pro that I couldn't be happier with if I had paid $500!