Sam --Rob did performance comparison tests on the dyno and he said he saw the difference with the NGK's performance.I've got an electronic ignition so I can open the gap or file back the ground rod a bit and my unit will fire pretty hot.----- I've got no complains with AC, BUT dynos don't lie, Rob said it performed super. I did however find that the AC 44 or 45 did keep a "STREET TUNE" longer than the NGK IN MY CASE-- also AC 43 is a little too cold if your not gonna blow out the carbon now and again....----------I would guess Rob would be able to give you a number for your Z............
