Yeah the MAP sensor only reads to 1.5 bar gauge (2.5 absolute) but it doesn't matter. I've requested and run 1.7 bar boost (gauge) with no problems before. Have a chat with Vince at Stealth as he can explain it better than me. It's not a big deal.
What RPM is the fuel cut occurring? Sure it's fuel cut and not the ECU combatting compressor surge? K04s exceed the engine's VE at approx 3000rpm if running greater than 1.4 bar and the ECU goes into 'what the f'ck is happening here mode', which feels like an abrupt stutter, and then the power resumes.
Stock and Stage 1 don't hit that problem because they only request 0.9 bar and 1.2-1.3 bar respectively. It's why I keep banging on and on like a stuck record......just don't do 2+ maps! You can pull back the N75 duty around 3000 to get around it but it just feels like a nasty flat spot when you do that.
Dunno how you got -1.8 with the SP BJs, most I could get was -1.2
You definitely need a HPFP if you're running 1.5 bar regardless! I recommend the Integrated Engineering one as the piston shaft is the same diameter top to bottom, which is a lot stiffer and stronger than the usual method, but the VIS one isn't too bad for the price.
