Helping a buddy with his shelby z, recently installed +40s, 3 bar, and a cal. We drove it and with the boost turned up to only 15 we started getting some spark blowout. We checked the plugs and found some bosch platinums gapped at .046. I headded home and told him to get some rn9yc's and gap them to .028. Just now he called back saying the car runs like absolute crap now, can't go over 11psi and misfires really bad. I told him to open them up to .030 and try again but he hasnt called back yet. What is going on with that, I've never had problems with rn9yc's at .028?

His coil is an accel super stock, I ran one for a while with no issues so I don't think that is the problem. Cap and rotor are new and the wires are brand new magacor's.