Bolts can be set by in number of ways, torque, angle or stretch are the ways that I have heard of, you may know of more.

ARP do recommend the stretch method, but not many people have a stretch gauge to hand, but hopefully they will have a torque wrench which will suffice for engines being built for a fast road car.

It is also important, as has been mentioned above, to torque the bolts with the threads prepared to the bolt manufacturers recommendations, and the torque procedure followed to the letter.