Just finished this little chore again. Tried the diamond bits, but they really did not do a good job. The cobalt drills are fantastic. They cut right through the hardened stud. My problem was that I was not exactly on center, so the stud remainder never did loosen. The thing was just like welded to the aluminum.

Time Sert to the rescue. Once again, these little units did a fantastic job of grabbing the metal inspite of my less than perfect workmanship. Managed to use a standard manifold stud too. Did not tempt fate by playing with the other studs. Just gently torqued the manifold on. Tonight the upgraded Cherry Turbo goes on --- test drive tomorrow??

dick