ARP Head Stud Kit. Fitment : 06-14 Honda TRX450R / ER. Kit Includes: -ARP 8740 12mm Head Studs. ARP 8740 12 Point Nuts -ARP 8740 Washers. ARP Ultra Torque Lube. This Kit was developed by JSD Machine Works and made by ARP. These Studs are 12mm Case and Head Threads (compared to 12mm Case and 10mm Head Threads) to allow for increased clamping load on head gasket. These Studs allow much higher torque on the head studs than the OEM Studs to increase head gasket clamping force. Studs also do not stretch under load to prevent head gasket failure when using higher compression, larger displacement, nitrous, or boosted applications. These Studs allow increased torque to 50 ft/lbs. ARP Studs are the highest quality head studs available made in the USA. These Studs require Cylinder Head Machine Work to clear the 12mm Threads on the head side of the stud. Stud Holes in Cylinder Head must be drilled to 1/2 Diameter. Modification Instructions (for Drilling Cylinder Head) are included with the Kit. OEM and most aftermarket cylinders Athena, Cylinder Works, etc. Do not require machine work to the cylinder to clear 12mm Head Studs. The only exception is with the CPI Spec Cylinders offered by several companies (JSD Machine Works, Racers Edge AZ, Sparks Racing, and JSR Performance) require drilling of stud holes to clear 12mm Studs (Instructions are included for this as well). Uses Stock OEM Dowel Pins. JSD Machine Works offers a complete line of OEM and Aftermarket Performance Parts for the ATV, SxS, and MX Bike Industries.