Ya that bolt on the bottom of that harness is tough. I got it off with a 10mm socket and ratchet as well, but you can't get many clicks on it, so it takes a little while. I ended up breaking that stud off too, and just filling the hole. That main engine harness has really been a PITA for me this year. It was in the way too many times for that motor mount install, and boy did it ever get in the way 5 million times during the turbo install, not to mention the actual wiring of it too.