I have never seen or heard an original AMG exhaust from a 230 Kompressor, at least not here in the U.S. To my knowledge, the 230 and 320 R170s were never offered with an AMG exhaust from the factory. If you saw one, I would guess that someone put a SLK32's exhaust on their car, or it was a custom fabrication of some sort.
As far as the R170's exhaust fitting is concerned, all R170s have the same exhaust cavity for the muffler itself to fit up underneath the car, but with two caveats:
1. The 230 and 320 (as far as I know) come with a muffler that has a single exhaust tip. Unless you have a model with a factory sport package (sport rear bumper), the chances of a dual-tip exhaust unit fitting without touching the sides of the bumper cutout are questionable. The sport package 230's and 320's have a slightly wider cutout on the rear bumper which can accommodate a dual tip exhaust. If you want to replace the 230's muffler with the 32's AMG muffler, depending on your rear bumper you may have to cut and enlarge the hole in order to have proper clearance.
2. I'm pretty sure that the 32's AMG exhaust has a larger diameter connecting pipe than the others (the pipe that connects the resonator to the muffler). So, although it does bolt on and fit underneath the vehicle, it may not attach correctly without a custom adapter from the smaller pipe to fit into the larger opening in the 32's exhaust unit.
So it depends on the cutout on your bumper. The R170's had 3 different bumpers, from what I remember historically.
Here is a Pre-2000 model SLK230, non-sport:
As you can see, these models feature the black "band" around the entire vehicle as I noted in the photo. Also, you can see that the exhaust cutout only accommodates one tip without modification.
Here is a 2000 SLK230 Sport:
The rear bumper of the sport package features two "ridges" that mimic the style cues on the hood of the SLK. Also notice the somewhat wider cutout for the exhaust
Here is what the 2000 sport package rear bumper looks like when you put on a dual tip exhaust:
As you can see, it does fit, but you have to really be careful and adjust the hanger lower so it does not touch the bumper, or you'll have melted plastic! This is an Eisenmann exhaust for the 230, which is even wider than the 32's AMG exhaust tips at the outer corners (at the 10:00 and 2:00 positions) so a factory 32 AMG exhaust should fit, as its tips are more oval than rectangular.
Here is a 2001 SLK320
This is a facelifted model year with a newer bumper. The black "band" is gone and the entire piece is the same color as the body. Unfortunately, the exhaust cutout is still only for one tip. Cutting into this bumper would look a lot more noticeable than the previous black banded bumper.
Here is a 2002 SLK32 AMG with the factory exhaust still on.
Notice the rear bumper has a small black plastic piece only in the middle, and the exhaust cutout is designed to accommodate dual tips