70 PSI is the performance straight out of the pump sitting on a bench. When you add plumbing, etc., the pressure will decrease about 15%.
After plumbing we expect about 15% less pressure - maybe 55 PSI. In reality, if you are using the boom, you only need about 40 - 50 PSI otherwise the droplets will start misting because the pressure is too high. On the other hand, if you are using the spray gun, you may want more pressure.
There is a screw on the pump you can adjust to raise the PSI - turn it clockwise to raise the pressure. It comes preset from the pump manufacturer as you see it.