I have an AXX in for custom mapping with k04 and S3 injectors, I am mapping it to around 300lbft 320bhp with 130bar rail pressure via the Autotech internals, the car is fine for the first 5 mins driving / 3-4 dynos runs making 130-135bar on demand, but then the actual pressure starts the drops of the 130bar request by around 30bar across the whole range and is very slow to even build up to 90-100bhp. I have changed the cam lobe and fuel pump and still getting same issues.
Has any had or read of this issues before?