I have used Fel-pro stuff over the years, head bolts included, no complaints
If turbo or super charging then studs are better IMO
Yes, any time you look up the torque specs on a bolt and you see "Rotate XXdeg" as part of sequence, then its a TTY bolt and can only be tightened one time
Its a better bolt than standard because it stretches so can hold tighter when metals around it heat up and cool down, like say, in an engines head, lol
But once its been stretched once it can get brittle when loosened
You CAN re-use a TTY bolt, but it may break in final 90deg turn, or may break after 100 heat ups and cool downs, or may NEVER break, thats the roll of the dice
If its a new TTY bolt then no gamble