I have electronic ignition and I have mounted the computer behind the firewall, requiring the 8 wires to pass through the firewall. So, I made a drawing of a cable block to accept individual grommets without have individual shields at $10 each. Started construction using two .125 aluminum sheets 2 x 3 inches and some .017 Stainless as a decorative cover that should help with fire protection too. I sandwiched the three together and drilled attachment holes. I will then separate them and drill through one sheet of aluminum 3/4 holes to accept the rubber grommets. Each cable is .200" and will pass through individual grommets.