What are the specs to torque headbolts on Audi 1998 A6 2.8 quattro DOHC?

For the 1998 Audi A6 2.8 Quattro DOHC, the head bolts should be torqued to 30 Nm (22 ft-lbs) initially, followed by an additional 90 degrees rotation. After that, a further 90 degrees should be applied to ensure proper clamping force. It's crucial to follow the proper tightening sequence to avoid warping the cylinder head. Always consult the vehicle's service manual for the most accurate and detailed specifications.