I installed these also this past weekend. I figured that I would just add to this thread instead of starting a new one. I ordered them off of EBAY for an SLK, $280 included shipping them from Germany. It's really easy to install these.

I also bought a used cover off of EBAY from an SLK 320 for $38 because it already had the exact cutout and trim pieces to go around the stainless plates. Unfortunately it did not fit, different mounting structure underneath. Oh well, it made a perfect template for cutting the Roll Bar holes.




Below are the tools needed. Basically just as Turbomar wrote, move the seats forward, remove seatbelt covers(2) by removing door flange (3 screws), remove hooks and buttons (6 in total), lift crossbeam cover straight up, remove sub grills, peel carpet forward to access 8 bolts holding the roll bars. These are the tools needed.





There is a phillips head screw inside the seat belt holder. Once you remove this screw, grab the seat belt holder trim panel that mates up with the rear glass and pull it straight towards the front of the car, then just let it drop to the floor at the bottom of the seat belt.




These are the bolts that you will need to buy to install the bars. The Roll Bars didn't come with bolts, since they are replacement bars, it is assumed that you would reuse the stock bolts.




The pouch took a little bit of figuring out. The clips need to slide in the direction of the arrows to remove them.


Once these are removed, drill the holes in the header panel, slide the bars into the stainless trim plates, then into the header panel, then lower them in place. Bolt the bars in place, put the carpet back in place, lower the header panel and just install all of the trim pieces.