There are several areas of the electrical system in the 928 that I consider substandard. One of them being the battery cable that connects the battery to the starter. Porsche used a 4 AWG cable and I upgraded it to a 1/0 AWG, as I was able to measure a 1.5 volt drop from the starter to the battery. As you can see, from the battery compartment it looks a bit more beefy than the stock one. It is the one with the pink heat shrink. The battery clamp was filled with solder, and I heated it up with a torch. While the solder was still hot, I jamed the stripped end of the cable into it, until solder was coming out around the insulator. I held it into place until the solder cooled. Its in there! The other red cable is the amplifier power cable.
Below, I used larger insulated cable holders, which I found at a marine supply, and used all of the factory locations to secure the cable to the car, as seen below.
Below, you can see that I routed it using the factory route, substituting larger clamps. It looks close to the differential where it comes out of the battery box, but it is actually about 3 inches away from it.