I tried going Stage 2 COBB map. Everything was fine ..fuel pressure held, then during one 2nd/3rd/4th WOT I found fuel pressure dropped dramatically.
I also couldn't explain the hesitation I would get on a single 3rd or 4th or combination 3rd/4th WOT, with no fuel pressure drops. I put it down to the extra demand in fuel pressure from the Stage2 maps.
I've since gone back to Stage1+TIH+IC and it's smooth as silk. No hesitation, no fuel pressure drops - 2nd/3rd/4th..flat foot nice and smooth.
Just waiting for my fuel pump to arrive before going down the exhaust +dump pipe + stage2 path.
Like you said, I think it's combination of bolt ons that tips it over the edge and then starts to put demands on fuel pressure.
Trying to keep it subtle ... | COBB AccessPort | COBB DP | CP-e HPFP | CorkSport TMIC | TurboSmart BPV | Denso ITV22| CorkSport Boost Tubes | SURE Full3 Aeros | SURE REM (Street) | SURE AGS SS Shift Knob | 2XS SSP + SURE CounterShift | Speedline Front Strut Brace | Whiteline RSB | Prima Paint Protection