I switched from the OEM plugs to the 5992's and like them so far. I am typically pushing about 17psi when running e85, 15 when running straight 91. I sometimes notice a bit of backfire after I changed the plugs, but I'm not sure if it's related to that or the fact that I also adjusted my wastegate at the same time I installed the new plugs (should have waited so I could isolate the plugs better). Nonetheless I love them, my misfire issues when running e85 have diminished (used to misfire at the top of 3rd, or any sudden WOT in 3rd, but may have been blame to the 20k miles I had on my OEM plugs..) I gapped them to 0.022".
'08 E92 335i Pre-LCI | Sparkling Graphite Metallic | VRSF Downpipe | JB4 G4 | Mr. 5 Intake | 50/50 e85/91| Alpina B3 TCU Flash | NGK 5992 Plugs | More to Come...?