These head studs were developed with years of racing in mind, where the stock head stud leaves off, this stud picks up.  If you're looking for the absolute best performance in head gasket sealing, this is the solution.  This is not meant for someone going under 1,000HP but for those looking to push the limits of the platform.  The ½” stud will require machining the block to accept the new stud. This has to be done carefully so you do not crack or damage the block.  In addition, the dowl hole will need to be opened up and a custom dowl purchased or made (available at Titan Motorsports). The head also needs to be machined to accept the wider stud as well as the head gasket.  This combination, after machine work is completed, is the best combination for holding horsepower on a cast iron 2JZ block.  

These Titan Head studs require you to have your block and head to be machined for 1/2" studs and a custom head gasket (Sold Seperately)