Originally Posted by Satalite
So there are 2 kinds of HID kits that you could possibly use? OEM BMW HID Kit (MTEC)? VS eBay (MTEC)?
What are the differences.
Sorry for the confusion. No. MTEC makes a generic H7 HID retrofit kit, and they also make a BMW-specific H7 retrofit kit. The OP in the thread that you're referring to never responded to my inquiry about which kit he used so I just picked up the BMW-specific one to be sure. It's possible that the generic kit will work as long as the proper coding changes are made to the car, but I didn't want to go through the hassle of trial-and-error so I just ponied up for the BMW-specific kit. P.S. The eBay auction for this MTEC seller had (has?) a Make an Offer option, which I exercised. I ended up getting the kit for about the same price as the regular, generic retrofit kit, including shipping.
The BMW-specific kit includes a relay harness that powers the ballasts via a fused (one fuse circuit for each ballast) connection to the positive battery terminal under the hood. It also includes what the MTEC documentation refers to as two "control boxes" and two "rectifiers." I imagine they are used together to perform some CAN-BUS trickery. Again, I can't tell if the kit components or my coding changes are what make the kit work because I made the coding changes prior to the install. I've thought about reverting the coding changes to see if the kit alone would be a cure-all, but I figured why mess with something that works. Also, I really like the idea of having a relay controlling the equipment because it electrically isolates the HID kit from the vehicle's actual lighting circuitry.
Finally, because I think I neglected to include this in my original post, I mounted the ballasts, control boxes, and rectifiers to the forward side of the front fender liners. I simply drilled some small holes in the liner and then used black zip ties to secure the equipment. This way the equipment is out of the way, hidden, and secure.