[Mark O'Neal]

Bolts stress the threads, on the bolt and in the block, when they are secured. Studs move the stress to the studs.

Studs are better, although not always necessary.

Also, ARP just intruduced a stud with a hew broached into the end so you can pull the stud to get the heads off, instead of pulling the engine.

One of those simple things that make a lot of sense.