Grounds are important.

Lately I've helped a few local guys and many of them have had problems with noisy signals, misfires, etc. While this may not be a direct result of poor grounds, it defiantly doesn't help the situation.

The factory ford harnesses are not very good to begin with. The sn95 cars have it even worse because of the remote mounted tfi, which gives you another ~2ft of crank signal wire for problems to occur. Many of the mustang guys have rear mounted batteries, and I cannot believe how much ghetto rigging of grounds I've seen!!!

IMO, with a rear mounted battery, you really should run a full length ground wire back to the engine block. ( 2ga min) Since the battery is in the right rear of the car, you should also have the battery ground go to a good chassis ground. On my car I ran the ground from the battery, to the unused hole for my quad shock, then ran from the quad shock up to the block. It's also a good idea to run a 10ga min wire from the neg battery cable up to the ems grounding location. (stock is kick panel area)

This will significantly reduce noise in the ems signals, and may take care of some possible issues with misfires etc.

The wide band should also be grounded at the kick panel location to minimize voltage offsets between the ems and wb.

This is what I've found has worked best for me and the cars I've worked with.