Ok well mods are:

CC306 918 springs NSA valvetrain
Edelbrock Shorties
!Cat
Magnaflow Catback
Cutout
36# SVOs
CAI
CSR EWP
LS1 DS (M6)
Vented Opti
MadZ28 Tune

Car runs strong up to 5k or so, startes cutting out big time. Datalog shows around 6* (max) of knock retard at that time until I let off or shift. No exhaust leaks, no unreasonable valvetrain noise. Plugs have 3k on them, gapped properly. Wires are brand new, routed properly. Opti is brand new, coil and icm have 3k on them. So since ignition is all new, I do not believe this is a missfire issue. Also, with my valvetrain float should not be an issue. So that leaves me with fuel right? Car is tuned for 36# injectors, which are no where near being maxed out. So could I actually be getting REAL (for once the darn things work? ) knock retard due to a failing fuel pump? Ah fuel filter was replaced 3k ago also so that's not a problem either.

So my diagnosis would be to check my fuel pressure at WOT right? Another thing, I know that the O2 readings are pretty much crappy to tune by, but they both read right around 910 mv all the way up the curve, which I believe is acceptable? So if my fuel pump was really cutting out why wouldn't my O2s start reading a bunch leaner? Basically this is dumb because I spent mucho time getting my 306 installed so that I could rev to the moon, and now I can't rev higher than 5k help me

Also, this isn't as bad in 1st gear, actually almost an intermittent problem in 1st, but at "sustained" high rpm like in 2nd or 3rd it's definitely there all the time. Leads me to fuel pump again right?