If you really want to improve the performance of your Nissan R35 GT-R using the stock head gasket, the factory bore sealing proof stress restricts the improvement. GT800 Package can release the restriction by replacing the Head gasket with the Metal Stopper Head Gasket which enables higher performance. This HKS Head Gasket includes the Exhaust Manifold Gasket. Best to use with GT800 Package to upgrade the engine properly.

• High engine output parts. Designed to replace the factory Head gasket.
• The bore diameter and thickness are the same as the factory gasket.
• The shape of the exhaust gasket is the same as the factory gasket.
• Improved the bore seal proof stress at high output and high boost by redesigning the structure without upgrading the Head Bolt. (Bore seal pressure of the contacted surface was improved by 30%)
• An in-house test at 900PS confirmed durability and safety.
• The compression ratio of HKS Head Gasket isε9.0 which is the same as the factory ratio.
• The Exhaust Manifold Gasket uses the 4-layer seal bead design (t=0.8). (The factory is 3-layer design (t=0.6)
• To maintain the bore seal proof stress, the stopper's height was changed to 0.15mm from 0.10mm. Narrowing the width enables the high-proof stress with the factory Head Bolt axial tension. Also, optimizing the bead plate's angle improved the seal pressure of the contacted surfaces of the oil and coolant seal parts without affecting the bore seal pressure of contacted surfaces. The surface of the gasket was fully coated instead of only bead part of the factory gasket's surface like the factory gasket. A fully coated gasket's surface can improve the rigid connection of the cylinder head and block when installing the gasket.
• The Exhaust Manifold Gasket has a 4-layer bead plate comparing the factory 3-layer bead plate so the seal durability was improved to be used under high exhaust pressure.