Mine on 071's is a bit up and down on idle when gapped at 0.6, so I gapped to 0.7 idle was better but cuts out above 20psi, so have gone back to 0.6, so I can use all the power. I have a group A coil as well, so if you solve it let me know what plugs you use. As I have used C57's before but they did not last very long.