I wrote this, and then closed the wrong window...grrr. 
Anyway... The Paranoid Fabrications Legacy/Outback grounding kit is a good deal: for $25, you get a series of professionally made cables, all the right length, ready to install. What you don't get is instructions. I found the instructions on their site for the 2002-2004 WRX, and generally followed them...
I did discover, when doing all this, that while the exposed parts of the hardware looked pretty scuzzy, the mating surfaces were bright metal. I hit them with a wire brush just on general principles to make sure there was good contact.
Don't cut the terminals apart until you're ready to screw them down. This will make sure that you get the right cable in the right spot.
First, one of the 12mm nuts on the passenger side shock tower. (one picture)
Edit: Start with the end with the larger of the two ring terminals.
Route the cable down beneath the intake, and then to 12mm bolt holding down a bracket on the passenger side of the intake manifold at the front. (one picture)
There's a little screw, with a 10mm head, behind and to the passenger side of the alternator. The instructions said to use a 12mm bolt near the alternator, but I couldn't find what they were pointing out and there wasn't a bolt like that that I could find. The screw is hidden behind something else. (two pictures, one closeup, one wider with the screw hidden, but you can see the wires going to it)
Next, the upper rear bolt on the throttle body. This one's hard to get to; I wound up using a ratcheting 12mm box-end. Be certain to route the wires underneath the plug wires, and out of the way of any moving parts. The included tie-wraps are your friend here. (two pictures)
Next, a 12mm bolt holding on a bracket at the driver's side of the intake manifold, just behind the A/C compressor. (one picture)
And finally, the battery negative terminal. Be sure you get this one right! Bad Things will happen if you touch the positive terminal. (last picture)
The job took me right at an hour, because I was being slow and careful.
Anyway... The Paranoid Fabrications Legacy/Outback grounding kit is a good deal: for $25, you get a series of professionally made cables, all the right length, ready to install. What you don't get is instructions. I found the instructions on their site for the 2002-2004 WRX, and generally followed them...
I did discover, when doing all this, that while the exposed parts of the hardware looked pretty scuzzy, the mating surfaces were bright metal. I hit them with a wire brush just on general principles to make sure there was good contact.
Don't cut the terminals apart until you're ready to screw them down. This will make sure that you get the right cable in the right spot.
First, one of the 12mm nuts on the passenger side shock tower. (one picture)
Edit: Start with the end with the larger of the two ring terminals.
Route the cable down beneath the intake, and then to 12mm bolt holding down a bracket on the passenger side of the intake manifold at the front. (one picture)
There's a little screw, with a 10mm head, behind and to the passenger side of the alternator. The instructions said to use a 12mm bolt near the alternator, but I couldn't find what they were pointing out and there wasn't a bolt like that that I could find. The screw is hidden behind something else. (two pictures, one closeup, one wider with the screw hidden, but you can see the wires going to it)
Next, the upper rear bolt on the throttle body. This one's hard to get to; I wound up using a ratcheting 12mm box-end. Be certain to route the wires underneath the plug wires, and out of the way of any moving parts. The included tie-wraps are your friend here. (two pictures)
Next, a 12mm bolt holding on a bracket at the driver's side of the intake manifold, just behind the A/C compressor. (one picture)
And finally, the battery negative terminal. Be sure you get this one right! Bad Things will happen if you touch the positive terminal. (last picture)
The job took me right at an hour, because I was being slow and careful.
