head bolts/studs
 

Does anybody know the difference between ARP2000 head studs and the custom age head studs? Is there a big enough difference to justify the cost difference?

ARP2000 Head Studs are 220,000 psi tensile strength

ARP custom Age Head Studs are 260,000 psi tensile strength. (For higher HP)

And price is the other difference lol

Have to tap the block for the bigger studs I'm pretty sure.

Theyre not bigger just different material. If you have an unlimited budget the customs will add some extra insurance but, Ive seen the regular 625's hold up just fine in compound setups and other various high horsepower applications.

I believe your are just chasing the bottom few threads to take advantage of them. This would be done with a bottom tap as GM uses a taper tap and the last few are not complete