So 3.3T stock ecu no jb4 or any tune, but I do have 5346 Denso's installed on a stock ecu. Had them installed before hand, before I purchase a jb4. Had them on for about 600 miles or so (the new plugs) gapped to around .020 is what I was told by the shop. I just recently started to get a miss fire at WOT when I step on the gas off the light, car cuts power throws a CEL for a brief second then power comes back on. Anyone else experience this problem with upgraded plugs on a stock car? Just curious, probably just a bad plug. Gonna take the car back to get it checked out again. Car was running great though with the new plugs, felt way more responsive than stock.