I would recoomend these http://www.blaupunktusa.com/Blaupunk...ent/PCc660.htm
Mount the tweeters up high and add a sub. You can still use the original grills. Not as hard on the wallet as the MB's.

 

Here’s the stereo setup on my 90’S4:

Blaupunkt Honolulu (4x40W)
- speaker output for front and rear with fader adjustment
- pre-amp outputs for external amp.
Head unit directly driving
-front 4” woofers & tweeters
-rear 4” woofers.
Sony XM-222W 2-channel power amplifier
- located in factory booster amp location
- driving rear 6.5” woofers and tweeters
Speakers:
10 speaker system using factory locations, crossovers, and factory grills
Speakers:
2 - MBQuart 6.5” single cone woofer mounted in cutout of factory speaker
2 - 4” dual cone, 40W, 1.5” mounting depth, mounted in front
2 - 3-1/2” dual cone, 40W, 1.5” mounting depth, 4” woofer locations.
4 - factory 2” tweeters front and rear

 

Check out www.partsexpress.com for the foam surround repair kits. They also sell perfed metal speaker grills in all sizes. They look fairly close to the originals, yet are pretty indestructable. I used them to replace all of the factory grills in my car. I used to own a car stereo shop and the 928 is a pretty tough car in a lot of respects, not much room, pain to integrate aftermarket w/factory, etc. I have found a great little 5 channel amp bt INTERFIRE. I'm using it for front, rear, and mono sub. Probably 300 real world watts.(dealer cost $130.00) Hope I helped, Rick

 

I just purchased MB Quart PCE 210's for the doors and the PCE 216's for the rear for my 88. I hope to have them in next week.

 

Just remember they are NOT efficient! Need lot's of power if your threshold is 105 db. Mike