I’ve never heard a stock stereo system that I could tolerate for very long. I had a decent system in my 91 MR2 turbo when I got the opportunity to upgrade to a 93 Turbo with low miles. I sold the 91 and removed the system. That gave me the basis for the nearly complete system that’s on my 93 Turbo today. I started with: Kenwood Excelon KDC PS909 AM/FM head unit with CD changer control. The reasons I chose this unit were it’s 105dB signal to noise ratio and the MASK rotating faceplate. ***I've since upgraded the head unit to the Kenwood KDC-MP919, which can play MP3 encoded files, while retaining the 105dB signal to noise ratio of the earlier head unit.*** In addition to the head unit, I had an MTX Pro504 amplifier, which is rated for 4x50 watts into 4 ohms at 14.4 volts. The unit bench tests at 4x80 watts at 14.4 volts into 4 ohms. Two channels crossed over at 100Hz run the two 6.5 inch Boston Acoustic mid-range speakers and the Polk Audio dB series 3000 tweeters. The other two channels provide rear fill via a pair of Boston Acoustic CX3 3.5 inch coaxial speakers crossed over at 200Hz. The Polk Audio tweeters were chosen for the mellow sound provided by their rubberized silk domes. They are flush mounted in the kick panels to minimize signal path length difference and on-axis response between the two channels. Crossover point is 5Khz. To get some additional power, and two more channels, I added an Alpine V12 MRV1000 amplifier running at 150x2 watts into 4 ohms. This amp powers a Rockford Fosgate dual voice coil Punch series 10 inch subwoofer crossed over at 80Hz. The sub is mounted in a custom enclosure, that was designed in Auto-CAD, to exactly match the Thiele-Small parameters and Q that is specified by Rockford Fosgate for this particular driver when installed in a small, sealed enclosure. The amplifiers are mounted on a custom ½ inch thick plexiglas amp rack, located in the front trunk. (I carry “Fix-a-Flat” and a cell phone and have free towing in case of flats.) The rack secures to the OEM tie-down for the spare tire. Despite my high quality shielded interconnects, I was getting some feedback from the electric pump that pressurizes the power steering. The pump is in the front trunk and emits an incredible amount of RF. I finally encased the pump in 2 layers of aluminum foil and did the same with the interconnects. This solved the noise problem. ***update, I've since converted the car to manual steering, using the manual rack and pinion steering rack from a wrecked MR2*** I eliminated any chance of ground loops by grounding every component to the negative battery post via a distribution block. There are two layers of Dynamat Super in each door and a single layer on the floor and firewall. This lowers the noise floor of the car by 3dB, effectively doubling my amplifier power. The car is amazingly quiet with the stereo off or paused. I installed a Kenwood steering wheel remote that looks OEM, and allows me to fully control the head unit without taking my hands off the steering wheel. Right now I have a system that sounds fantastic and runs the ¼ mile in under 14 seconds. Stereo:

Kenwood KDC MP-919 AM/FM/CD/MP3 Player

Custom Plexiglas Amp rack

MTX Blue Thunder Pro 504 Amplifier (80 Watts x 4)

Alpine V-12 MRV1000 (150 Watts x 2)

Polk Audio dB Series 3000 2 inch tweeters

Boston Acoustics Pro Series 6.5 inch Mid-Woofers

Boston Acoustics Pro Series 3 inch Coaxial rear fill speakers

Rockford Fosgate Punch Dual Voice Coil 10 inch Subwoofer

Rockford Fosgate Dual Amplifier Connection kit

StreetWires Zero Noise 2.0 shielded RCA interconnects

2 layers of Dynamat Extreme in each door, single layer on floor and firewall