dyno is not correct as you cant get anywhere near 250bhp with just a compressor, 220 is about tops
injectors are fine as standard, kit was sanctioned by TTE and they dont recommend changing them
if its not the TTE box i would look at the throttle cabling, make sure its not tight and has slack
failing that, you may need to get someone to look at the EMU, best get someone who knows the greddy equipment