I have 99-00 wrx running autronics smc plug n play. In the near future i'll be upgrading fuel lines, fuel pressure reg, fuel rails,fuel pump, injectors, turbo, boost solenoid, and air intake.

At the moment it's tuned to 440cc side feed injectors, when i change to ID1000cc top feed injectors can i just select injector dynamics 1000cc@300kpa from menu. wrx base fuel pressure 3bar 43psi.

And with ID1000cc being 56% larger than 440cc. Can i decrease overall fuel calibration multiplier by 56% and hopefully still have alright air/fuel ratio.

I just want wrx running safe enough so i can drive to my tuners workshop.

Should be safe as a base map , Just be aware of the rail pressure if changing lines and FPR measure the rail pressure and just drive off boost to the tuner.

fuel pressure regulator i'm installing is turbosmart Fpr1200, it's adjustable 1:1 ratio. Little bit overkill but it has -6AN inlet and outlet ports which suites my fuel rails. Will also have pressure guage.

I'll set fuel system to 3bar. 43.5psi

Thanks for the info.