Very nice system and car. I still have my 87 Supra Turbo with 167K miles. It's sort of in retirement now and it's driven only a couple of times a month. I may have to sell it next year if we get another car. I am guessing that the gasket blew around 80K miles. This is a common problem with Supra. I am pretty lucky in that I have not had to replace the gasket or the turbo charger yet.
My Supra has Soundstream pre/cass and an Alpine CD changer. Speakers are ADS, B&W and Eaton drivers. Amps are Soundstream and a HK 3 way electonic x-over. Cables are Kimber 4TC and Monster Cable M1000.
Rich