I just finished installing a WRX stereo in my wife's SVX. What a huge difference in sound quality over the stock setup. It looks great too. Thanks SVXdc for the wiring harnesses. I was lucky and bought the stereo for $100 on ebay. Here are some photos of the process.
Bracket mod. I didn't cut all of the cage only enough to get the unit in. Also notched for antenna.
Stereo mounted inside of cage.
Modded dash. I didn't cut the tabs I only bent them out of the way.
Installed
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I'll add a night photo later.