The MLS gaskets require perfectly decked surfaces on the jug and head. I'm unaware of the HD stud requirement, maybe so?
Cal, I read somewhere here that since they are made of steel they will experience less compression under the normal studs torque. That's why it's better to have em with HD studs so they can be tightened to higher torque.
You may well be right. I've not used one without HD studs, so I have no knowledge if you can/can't.
