A set of 8 air injection plugs for most 308QV.  (not for 2v vehicles and very early QV production.  Check your existing ports before ordering)

New style manufactured plugs are brass and includes copper crush washer.   There is sufficient recess to ensure that port to port & plug length variances won't make the nose protrude & interfere with exhaust flow, but it's not enough of a recess to cause whistling or other problems.