Page OneThis is the subject a gold 1992 BMW 525iThe tunes are supplied by an Alpine CDA-7998This is the trunk in stock fashion:completly unaware of what waits in the wings.The first step was to entirely strip the trunk and bring in the RCA and upper frequency drivers speaker wire. Mids and tweets consist of a pair of Diamond Audio 6 1/2" seperates up front complimented by a pair of Diamond Audio 5 1/4" coaxials for rear fill.Next we started sound deadening the trunk. The spare tire well recieved a 1" MDF floor which was glued and screwed into place. (to anyone attempting this I cannot emphasize enough how important it is to thouroughly anchor this piece).Along with Dynamat expanding foam was used to fill any voids and quiet things down.The first box building steps: This is the bottom of a shallow 4" box which is to set over the spare tire well.If you look closely you will see the glue is being applied to a dadoed rabbit joint. It does take a few extra steps to rabbit all box joints but it not only gives you more surface area to glue to it also makes the box stronger as well as eliminating any possibility of air leaks.The boxes are now ready to go into the car. All boxes are constructed from full 1" thick MDF and sealed thouroughly.These .5 cubic foot after displacement boxes each house an Arc Audio 10" driver for midbass and are used to play frequencies from 50 to 80 cycles per second.It now becomes apparent why the boxes were not painted as each enclosure is hidden behind cover panels clad in automotive carpet.The BMW has alot of sound deadening from the factory however we still covered any large or uncovered panels on both sides to eliminate future rattles or ringing.This is the box which will soon hold four Arc Audio 12" subwoofers. It is 3.8 cubic feet after all displacements which gives the subs .9 cubes each this arrangement nets a near ideal QTC of .7 as dictated by WINISD (my modeling program of choice and is available as a free download).Cardboard is used to make templates which will be transfered to wood and hold the amplifiers.Cardboard is the installers equivelant to duct tape.Here you can see that the subwoofer enclosure is about 4" higher than the trunk floor.The woofers are held in place by allen head machine bolts and furniture grade T-nutsThe box is loosely filled with long stranded natural wool.Final placements of electronic components are tested.This is the other half of "we" Danny Durbin. Without his help,hard work,and problem solving skills this project would never have got off the ground!Here you can see the false floor made of what else? Flooring! Floor panel is only slightly thicker than wall paneling but is MUCH stronger.The false floor allows us to hide unseen components like the Diamond Audio crossovers, x-static Batcap 400, and all wiring.All Done!! The amps; an Arc Audio 4050 for midbass,midrange,and tweeters. and another Arc Audio 1500D to power the subs. Anyone who tells you all amps sound alike have not heard a quality hand built amplifier!!Special thanx to:My wife Apryl and daughter Tori for putting up with my frustrations while riding around in a car with no back seat for two weeks!Danny Durbin..For help in all phases of design and build.Steve and Arron of Eureka Car Stereo..For helping me choose quality products and working on the complicated alarm system.Steve and the rest at Arc Audio..What a team!!