I'm surprised the fuel injection instructions didn't mention how you should run your negative wires. Ron Francis' catalog/'encyclopedia' has some really nice diagrams and products to help wire the negative-side of the DC system. Running all of your negative circuits back to the same stud (and then to the engine block and '-' battery terminal), for example, is also a good way to eliminate noise.

I think this is much more important for fuel injected cars than it is for carburetor cars; but a good practice none-the-less.