Thanks for that Martin, It's what I thought. So really the only difference between a 100psi pump, and a 60PSI pump is the pressure switch.
Once the switch has been dissabled to fit a Varistream, all Surflow pumps are the same regarding pressure. I Know pumps vary as far as litres a minute output goes, but There seems little point in Varistream users buying 100 PSI pumps. Dai