Note: There are some terms below that I have explained a little more clearly in the Tips section.
Alpine CDA-7940 CD Receiver - Well a buddy of mine sold me this deck for $150. It was newer then my older 7827, and had higher voltages for low-level pre-amp outputs. First reaction is that it rejuvenated the system, making it sound how it used to. This would indicate to me that my system is in need of some fine tuning, and/or components are getting old. I suspect my line driver is probably not tip-top. It's been repaired already.
Phoenix Gold PLD1 Line Driver - This little device is a must for someone that has engine noise in they're system or has a long way to run RCA wires. Basically, this is a low-level RCA pre-amp, it boosts the RCA voltage up to 8 volts. The basic theory is, the higher the voltage the less signal degradation occurs, and cleaner sound is outputted to the speakers.
Phoenix Gold EQ215x Equalizer - Equalizers can help a system a lot! They help get rid of the flat dull sound. This particular EQ also has built-in 24 db per octave crossovers at 90 Hz. It is a 15 band slider EQ, which is helpful, but was not the main reason I bought it. I guess initially I bought it for its Remote Low Pass Level Control feature. You can remotely adjust the gain of the subwoofer amplifier. It is very nice for music with too little or too much bass. You adjust it for your personal listening style. Another great feature is its 3 different outputs, Highpass, Lowpass, and Auxiliary. The auxiliary output is very nice for rear fill speakers. The signal can be chosen to be equalized/defeat, stereo/mono, and full range/band-pass. This component is a very nice piece to help adjust and fine tune your system for good sound quality and stereo imaging.
Alpine MRV-F401 Amplifier - This is a clean and powerful amplifier. I use it to power my front and rear speakers. The amp is rated at 40 W RMS, per channel with 0.08% THD into a 4 W load. This is definitely a conservative rating. It has front/rear adjustable highpass/lowpass crossovers, front/rear low-level inputs, and a set of RCA pre-out jacks, for another amplifier. I would definitely recommend this amplifier for someone that wants cleaner and more powerful sound and the ability to have more adjustment for your system.
Rockford Fosgate Punch 200x2 Amplifier - Well when you want bruit power and clean sound, you can't beat Fosgate. If you just want bruit power go with Phoenix Gold. This amplifier is unreal. Its rated power is 100 W RMS, per channel with 0.05% THD into a 4 W load. Now that may not sound like a lot, but remember this amplifier is bridged and run in mono, which means that power quadruples, so the subwoofer sees 400 W RMS, which is quite a bit. The Punch Amps come with a built in highpass/lowpass crossover.
Phoenix Gold 8 Gauge Power & Ground wire - Phoenix Gold probably makes some of the best wire around. They use fine strands so even when power wire gets large in diameter it is still very flexible. The only drawback is that it's about $1.50/foot.
Phoenix Gold In-Line Fuse Holders - This is pretty self-explanatory.
Rockford Fosgate RP7400, 1 Farad Stiffening Capacitor - A stiffening capacitor is very nice for stereo systems with a high amperage load. This helps the ever-annoying headlight dimming problem. The Capacitor acts like a small battery. When a heavy bass note hits, the amplifier has all that energy stored in the capacitor, rather than having to pull it all the way from the battery at the front of the car. The capacitor should be mounted as close to the amp as possible.
Two-Way Bosch Relay - This is a nice little feature to use if you have lots of accessories to turn on with your stereo turn-on lead. In my case I have 4 separate devices to turn on with that lead. Granted a turn-on lead just supplies power to activate the electronics, but that's still quite a load on the receiver. Your best bet is to use a relay, which is powered by an external power source. Doing this also helps in the dreaded turn-on "thump". There is a diagram and directions on how to read them in the Tips section.
Infinity Kappa 63.1i & 62i Speakers - The Kappa series speakers are some of nicest sounding speakers I have heard. They're not the loudest, but some of the cleanest. The 63.1i's are a 3-way speaker. They have a small woofer, mid-range tweeter, and Infinity's Emit-R planar tweeter. The frequency range on these is 20 Hz to 21 kHz, which is above most human hearing. These are my front door speakers. The 62i's are a two-way speaker, woofer and silk dome tweeter combo. These are in the rear speaker deck.
JL Audio 12W-D4 Subwoofer - JL Audio is also a very good name in subwoofers. They are one of the top manufacturers. The 12W-D4 is a 12 inch dual voice coil subwoofer. The dual voice coil setup is very impressive. The sub hits harder and louder then a single voice coil would. The main advantage of dual voice coils is being able to manipulate ohm load the amplifier sees. In a parallel wiring configuration my subwoofer would display a 2 ohm load. In a series wiring configuration my subwoofer would display an 8 ohm load. JL's flagship subwoofer has dual 6 ohm voice coils, you may see where this is going. With a 12W-D6 a parallel wiring configuration is 3 ohms. When the amplifier is bridged in mono it splits the ohms it sees from the speaker in half. Most amplifiers don't see half ohms, so the amp sees the sub with a 2 ohm load, which is usually as low as most amplifiers are stable at, when bridged.
Custom Subwoofer Enclosure - Most subwoofers work alright in any box, but when you design a box specifically for your speaker, it rocks. Well that's what I did. I bugged one of my buddies at the local stereo shop to let me use his subwoofer design software. With this I was able to see what type of enclosure works best for my sub, the amount of cubic air space needed, port length, and where the enclosure is tuned at. The enclosure is a Band-Pass type enclosure, meaning only certain frequencies are heard. If I remember the enclosure is tuned from 30 Hz to 95 Hz. This basically means those are the frequencies that are going to be most prevalent. Once I got all the information I set out to design and build it. I used 3/4" MDF, (Medium Density Fiberboard), sheet rock screws, clear house silicone, 1/8" plexi-glass mirror, 3/8" plexi-glass, 3M carpet adhesive, gray spay paint, speckle decorator paint, gray speaker box carpet, skill saw, table saw, and a 4" dia black PVC tube for a port. The most important thing is to get your design right. Make sure you calculate the cubic airspace correctly, subtract the speaker and port from your total airspace. Second, take your time. Don't rush things. I have seen too many cheesy boxes with good speakers in them that sound like crap. If you feel up to it you can save yourself BIG bucks on a good enclosure if you build it yourself. I spent around $80-$100 on materials. If I were to have a stereo shop build this exact box, I would probably pay in excess of $300, and that's probably not including material.
Rear Amp Rack Support Bar - Well when wanting to mount my subwoofer amp in the trunk, behind the rear seat, I ran into a problem. There was nothing to secure the amp's mounting base to. My Legacy has a square hollow tube bar that crosses between the lower part of the opening behind the rear seat. I needed something else at the top of the opening to help support the amp rack. I added a 1/4" piece of steel, which I painted gray. I drilled holes, and used bolts with locking nuts on them. I also used canopy foam between the bar and car to help with rattles.
Carpeted Rear Seat Backing - After punching too many holes in the cardboard backing with previous amplifier setups, I carpeted the backing to hide the holes.
Amplifier & Capacitor Mounting board - The subwoofer amplifier and capacitor are mounted on a piece of 3/4" MDF. The edges were mitered at 45o and the boards were carpeted. I then drilled holes for the wires to pass through from behind.
Rear Speaker Deck Mod - After putting speakers back in the rear deck I noticed my bass to decrease quite a bit. I needed some way to port the bass into the cabin of the car. Before I got the 62i's I had no rear speakers so the rear speaker holes served as ports. I fixed the problem by making new holes. I took out the rear seat and rear cardboard speaker deck. Then I used a whole saw to cut out two holes in the metal part of the rear deck. I then put the cardboard deck back on, made a mark on the cardboard where the holes were at, pulled the cardboard deck off, and then peeled back the carpet and cut a hole in the cardboard. I then glued two flat speaker grilles over the holes and glued the carpet back down to the cardboard, and voila, new ports.