The stock cylinder head studs on these cars are one time use stretch design. They need to be replaced with either new factory stretch bolts or you can source reusable hardware from the aftermarket such as ARP or Raceware.
A quick note on removing the old studs. The factory used red Loctite to secure the studs to the block making them extremely difficult to remove. You may have success with double nutting the stud to remove it. If not the only other option is to weld a nut directly to the stud.
Installation is fairly straight forward but the most critical step is to ensure that the holes and threads in the block are clean. I used a variety of cleaning methods including (Shopvac with a long tube attached) while using compressed air with a long straw attached to dislodge and collect any large debris. Then I used brake cleaner, rotated the engine over on the stand so the deck surface was facing down and collecting all the cleaner with a paper towel. If the threads are slightly distorted you can chase them with a M12 x 1.5 cleaner/chasing tap (Which is different then a normal cutting tap). Alternatively if you have old head studs around you can make a cleaner by cutting a few v-grooves with a file into the threads.
The studs, nuts and washers should be installed with a coating of ARP ultra torque fastener lubricant. This stuff is great, its superior to anti-seize and gives accurate torque readings. Install the studs into the block hand tight only and test fit the head gasket and head for any unusual binding. Don't forget to reinstall the 2 alignment pins in the cylinder block if you had it surfaced. If everything checks out begin the 3 step torque process (Follow diagram below for sequence). 20ft/lbs then 50ft/lbs then 75ft/lbs. Best case letting the head settle for several hours between each stage.
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