1. Took it for a runting to the Esex meet and it holds it's 5psi lovely if you razz it up through the gears. However if you hold it steady and boot it in 4th or 5th it just overboosts and cuts out

Any ideas before I make it something else for the SCC lads to look at?
2. Are the TPS the same on OFAC as on OFAB as mine may be iffy and a mate is breaking an OFAB managed car.
CheeRS in advance as always