Need some tuning help from some of you Professionals.

[Onefast99gsx]

It's been a while since i posted or even visited here. Been breaking the car in slowly since it has a new clutch and many other things. I've been tuning the car quite a bit over the last week with DSMLINK getting all my global and deadtimes within 1%. I've posted similarily on dsmlink without much good feedback so i thought i'd ask some of you that have way more experience than i do.

In every single log of mine i have knock and it's pulling back my timing. It's weird, it happens in almost the same spot everytime 5200rpm's. You could almost set your watch by it. It pulls back anywhere from 3 to 6 degrees(most commonly 3 to 5). It never happens in 1st gear at all period. It happens in the same spot though 2nd, 3rd and 4th gears. I've tried richening it, leaning it, i've pulled back a couple degrees of timing but all that does is just give me less knock. I just don't think i should have to pull back any timing for the current setup. Head was completely torn apart, ported, each and every lifter was cleaned thoroughly in a 2 step diesel process similar to factory manual method. Motor mounts are all new Protane mounts. The only thing i can say i discovered was a huge exhaust leak last night. The new gasket between the 02 housing and downpipe must have shit out or the downpipe loosened(haven't looked at it yet). I don't know if the loud noise from the leak could create some sort of harmonics that are interrupting the knock sensor? Fuel is 93 octane, boost is at 18.5psi.

Can any of you suggest anything to try or look at? I could really use some direction here.

Thank you!!

99GSX
PTE 50 trim, cut divider, internally gated
PTE 780 cc injectors
Magnus intake
HKS 272's
1g T.B.
Griffin FMIC 2.5" piping throughout
Walbro 255lph rewired
DSMLink
SouthBend DxD OFE Clutch
Fidanza Alum Flywheel
FP Intake pipe
Stage 1 ported head
Stock fuel rail, stock f.p. regulator
3" Exhaust
JAZ catch can
(2) 12" Mr Gasket 1400cfm each, fans
.... all the other supporting usual mods, etc..