The rear speakers are the ones that I found. I did not do the door speaker upgrade as it would mean getting later model door panels or cutting into my original panels. My 86 sdl came with just the 6 inch speaker in the rear deck and they were OK but the additional tweeters from the later model really made things nice. I would keep looking on E-bay. I believe I won an auction for just the two rear speakers at $25.00 plus shipping. They were worth it.
As for the subwoofer, all it added was some deep bass. There was a subtle change inside the car. There is so much insulation and your fuel tank in between the trunk and the interior. I do not play my music very loud, but I like to hear everything.
Keep up the good work on Coda!

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John
1986 300sdl
1985 380se