Man....GT25 is too small, I don't know how high is the compression in your engine (9.5:1???) but probs, somewhere in 200whp, 270Nm area....How does your leak down and compression test show??

Cheap things don't go so well 90% of the time. No proper ECU limits tuning + Somewhere if you push it to 250-300whp mark + non-conservative tune = Broken ringlands, shot a rod, melted piston, lifted head etc....