I brought mine up just below the firewall, right side of the trans tunnel. It is more or less hidden, although I did have the harness apart and rewired to make this mod.

Was this in the center of the tunnel? or to the left or right? What size hole?

Ive ran the Ecm wires several different ways. I Don't like using bulkhead only because that's just another place where there might be a "bad connection" It just like plumbing.. the more joints you use the more chances for leaks. I have ran the harness through the area just under the blower motor and through the kick panel. The other would be through the trans tunnel. I usually modify the arch of the tunnel so there is clearance. Sometimes the connectors are too large to go through a 1" hole. In the past I have made 2 plates with 2 half circles cut out. Once the plates are together around the harness you can install a 1" grommet.

Ive ran the Ecm wires several different ways. I Don't like using bulkhead only because that's just another place where there might be a "bad connection" It just like plumbing.. the more joints you use the more chances for leaks. I have ran the harness through the area just under the blower motor and through the kick panel. The other would be through the trans tunnel. I usually modify the arch of the tunnel so there is clearance. Sometimes the connectors are too large to go through a 1" hole. In the past I have made 2 plates with 2 half circles cut out. Once the plates are together around the harness you can install a 1" grommet.