Rear shock recommendation?
 

Bilstein or Koni

Koni or Boge

Boge Blacks, Anderson has 'em in stock.

Umm whats on the front?? whatever it is should match the rear.

That said If your running a S4 front suspension/springs ,
I would suggest a full set of Bilstiens for a fast mover street car, I like them the best

Like said, they should all match for proper handling.
Just like tires, you want the same type (not necessarily size) on all four wheels to maintain proper grip, right?

I have always regretted getting bilsteins, some day I will switch back to stock.....I am sure the ride will be less harsh ( also have low profile 18 inch carrera III)

Yes.

You need the same front and back.

I have relatively new (7 years and +/- 25k miles) black Boge and Carrera III also. Michelin Super Sport tires.
The ride is very good. I find them perfect for street use. Not fare from the stock 16".
This not a track car.

Tires brand / model can also make a difference here.

Although I understand keeping front and rear shocks from the same manufacturer a good idea on a street car (I certainly do this, in order to have similar ride characteristics,) I see no reason to keep the same brand of shock front and rear for more agressive driving.

After all, the shock valving requirements from front to rear are completely different.

Since stockist 928's understeer quite badly, I'd lean towards a more aggressive rear shock to shift the understeer back towards nuetral.

I'd think that an adjustable rear shock, like a Koni, would be a great place to start. The adjustability would allow you to play with the rear stiffness quite a bit....and the basic design of the Koni is similar enough to what you have on the front that the two would be completely compatible.
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I have Koni front & rear on my 928 Spyder with blue stripe sport springs & 18" wheels. Ride is very good.
https://cimg2.ibsrv.net/gimg/rennlis...774ab90326.jpg
https://cimg3.ibsrv.net/gimg/rennlis...7a2dfc4ec3.jpg

Pete it appears that your missing the dust boots for all of the shocks, why did they get omitted?
These covers protect the piston/seal from stones and from road water contamination.
Sand will damage the piston finish and then then the pitted area will cut the seals,
I have seen this happen on a new set of Ohlins a costly mistake

FWIW the adjustable Koni is made primarily to offset the wear,
IOW once they have been used and thus become worn.
You would remove the shock from the car and then add a turn to the piston rod after fully compressing it.

Since you have no idea how much damping is being provided by the shock when it comes out of the box,
the only way to find this out would be to install it first and road test it
OR put the shock on a load testing machine before installing it

NOTE their is a special tool available that screws onto the the piston and also slides into the allen slot ,
then the piston would be pushed fully into the shock and turned to effect adjustment.
This would be done with the shock/ spring assembly still under load in the car.

NOTE I would speculate for most spring/shock removal is necessary to make this adjustment.

NOTE their is nothing preventing turning the damper rod to full then installing,new shocks,
then road testing it for a few hundred miles then making further adjustments its just a PITA to do this,
and may require alignment if the shocks are removed from the car.

Stan,

Thanks. I'm not sure why. That's the way they were installed by 928MS during the original build.

Most likely because it's extra work to open the hole in the dust cover to get them to fit easier on the Koni shock. Each one I do I have to enlarge it by a micron or three.