Since I just got my SLK, and have never really worked on any R171s before, I decided to take off the front bumper and headlamp assemblies to scope out potential places to mount the ballast. (*NOTE: you do NOT need to remove bumper and headlamps to do this install, I will explain later)
The stock BiXenons have the ballast mounted directly under the headlight assembly. But I dont feel that it is secure enough for an aftermarket ballast that is bigger and without proper mounting holes...so the next best place is this beam behind the front cross member.
Many people use zip ties to install their ballasts but I feel I need more security so I used stainless steel piping rings.
To prevent metal to metal contact vibrations, I put some foam electical tape around the piping ring, which also gave the ring more grip.
Now, probably the hardest part of this install is securing the HID bulb in the Halogen Socket. Normally I see a metal clamp used to secure H7 Bulbs, but for some reason in the 171, it uses a metal retainer. The metal retainer in the next picture is already modified by me using a dremel tool. Originally it has a rectangular hole in the middle, I used a dremel to cut it so that the round HID bulb may pass through. **** IMPORTANT THIS IS THE KEY PART OF THE INSTALL ****
