How about the rest of your suspension components?

I replaced my entire suspension in my '82 244: all bushings, shocks, rear springs, ball joints, tie rods, steering rack, tires, strut tower braces. Nothing that you couldn't do, just get a spring compressor and be careful.

My '82 is generally much tighter now, quieter, and more fun on the road. I've got all the corresponding parts for my '86 745. I guess we both know where my weekend time will go for the next month.

I haven't yet done my sway bars.

My priority was suspension, since my sound system is still pretty OK. Upgraded a bit from original, but good enough for me.

However, if you want to consider rear speakers, look at the surface mount speaker boxes. That's effectively what my car has -- the factory rear speaker boxes project less than an inch below the rear deck. I buy my speakers (home, auto, and professional) from the Harman Kardon factory outlet in Oxnard, CA.
805.981-3800 or 981-1468. Great prices, full factory warrantee, and they ship UPS. Nice guys in a really awful outlet mall. Worth a trip if you are ever in LA: I bought my livingroom main speakers, floor mount, and powered subwoofer for about 67% off list price. Same deal for my Infinity replacement door speakers. Give 'em a call.
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-- Bruce / '82 244 (315k miles!), '86 745, '87 760Ti, '94 854