I do tend to listen to what the factory says in their manuals. I mean the factory
manuals. If Olds or whoever says to do it that way, I'd give it some thought at the very least. However, here I once used that exact same 'argument', i.e. "that's what the factory manual says" and was told "you cannot rely on what's in a factory manual to always be right". So d if you do, d if you don't.
In any event, I didn't take anyone's opinions as a slight to me. The options are laid out nicely, now it's up to the installer as to how to proceed.