Stock Diameter Kit
Studs are less prone to stretching under high boost applications. More accurate tensioning of engine. Less chance of bolt breakage. High quality 12-point nuts rated at 180,000 PSI tensile strength. Studs manufactured from 4140 chrome moly, heat treated, centreless ground and black oxided. Note the standard factory manual flywheel cannot be used with the Stud Kit. Includes 16 studs and 16 nuts. Uses the OEM tension bolt seals sold separately. 
The High Strength Oversized stud kit eliminates the need for doweling the engine block. All studs act as dowels which massively increases torsionial strength 70%. Rotor housing deflection reduced - increases apex seal life. Less material machined from housings and plates than with doweling, reducing the possibility of cracking. High boost engine expansion reduced. Studs are less prone to stretching under high boost applications. More accurate tensioning of engine. Less chance of bolt breakage. High quality 12-point nuts rated at 180,000 PSI tensile strength. Studs manufactured from 4140 chrome moly, heat treated, centreless ground and black oxided. Engine must be accurately drilled, reamed and tapped to give 0.2mm clearance. Includes 16 studs, nuts and sealing washers. Does NOT include/need the two at the bottom of the "legs" closest to the oil pan.
*Note: The standard factory manual flywheel cannot be used with the Stud Kit.
*Note: The S6/Cosmo 12.7mm studkit has 7 bolts that go all the way through the front iron.
The 20B stud kit includes 2x 11" studs that go from the rear iron to the #2 iron, 9x 17 3/8" studs that go from the rear iron and thread into the front iron, and 5x 19" studs that go clear through the motor and use a nut front and rear (These 5 replace all 5 factory 10mm bolts that went from the front to #2 iron). The two stock 12mm bolts that go from the front iron to the #2 iron are re-used, as are the two long bolts at the very bottom of the "legs".