I would say thatstock bolts can handle about 400HP. When installing ARP bolts, the rods MUST be resized. You would be really stunned to know how much changing any fastener from one tensile strength to another will affect housing bore size. We also use the stretch method as it is far more accurate. We chamfer all the bolt hole openings on the rod and the cap and we bore out the bolt holes in the cap just enoughtto make the rod slide over the bolts. Many times they are extremely tight and I can tell you that affects the sizes too.