I ordered the NGK Iridiums DPR8EIX-9 PDQ (parts delivered quickly) overnight from Advance Auto Parts. They were $6.96 each. I'll buy a set of the copper washers and index the plugs. Thanks Pat. Indexing will be especially helpful if the plug gap would have been hidden from the combustion chamber/exhaust by the ground if simply torqued in.
As Soren said, the plugs are a cheap and easy upgrade. Oh, I won't forget to use some copper anti seize on the threads. It will mess up your torque values some, so you may need to reduce the force a few Nm, but it could save the threads in the head.
