just installed 4 new speakers. disconnected the front tweeters and the hatch tweeters but left them in place for appearance. i installed infinity reference speakers - 4inch upfront - 6.5 in the rear. the rear i used the stock grills. the fronts i used the infinity grills. sound really nice! and i dont have an amp. would recommend them !
installation required some modification and the front were alittle tight but not a bad instll at all..im not sure if i like the silver trim around the infintiy grills - i may paint them black with some hobby paint to give a more stock appearance. i will post some pics at a later date. cost approx $160 from crutchfield - the infinity are on sale!
1986.5 928 5sp

 

I've had the Infinity 6.5's in the rear for about a year - they DO sound very good!