Remember just because you're rich doesn't mean you're not experiencing knock. And that knock might be partially from of the bump in compression or something else. Looking at your sig (copied here for future reference in case it changes):
2.5L SRT-4
stage 0 stage 1 injectors
JE Pistons 8.5:1 (.020 overbore)
Ported Stock Turbo w/2.0 cams
Walbro Fuel Pump, Fuel Return Kit, map clamp
AGP bling wastegate 21psi-19psi redline
CAI, QW FMIC, 60mm TB, 3"o2/downpipe/sideexit
My questions would be what do you have the MAP clamp set at and what is your fuel pressure? Also do you have adjustable cam gears with the 2.0L cams? I thought they have more overlap when run straight-up, and if they're causing increased EGT's that could be another potential source of increased knock risk. Again it's hard to diagnose online. Have you run race gas or decreased boost to see what timing does?
BTW, I just ran the numbers and .020 over pistons only bump displacement from 2.429L to 2.457L.
Technically I guess if you round up it's
maybe a 2.5L.
