18psi comes in at over 5500rpm and makes peak power north of 8,000rpm! Holy shit.
As a comparison my RB20 (old redtop) makes the same power at about 20psi but its all in before 4,000rpm and hits peak power at 6,000rpm. Its never seen 8,000rpm as the limiter is set at 7,000rpm. Turbo is the factory fitted dinosaur spec T3/T4.
At 4500rpm your car makes 60rwkw where mine and other cars with say the TD06 fitted have already hit 200rwkw.
I dare say the tuner could of brought your boost in a lot earlier with a .63 hot side but the 30/40 compressor may of gone into surge?.