What base pressure and afr bro?
But yea 250awkw is poossible with stock 444cc inj, even a little more......I'm doin roughly that now with them at 88% duty with 11.0 afrs,,,,and i'm sure your tuner wouldnt go that rich
Oooh ....an a walbro pump too....not in a gtr tho so i'm not sure about fitment