Alrighty people im looking for some advice. Why does sometimes a car boost to one point but then hold at another?

My FRST was set up to boost and hold 12.5psi - well thats what it was doing in November once AVA has set it up.

I got a new camshaft fitted - just a standard one due to financial constraints

When the car came back from the garage the boost has gone to peaking at 14psi and quickly dropping to 10/11psi It only hits 14psi for a split second but thats still higher than it should.

Any ideas on why this should be - or should I just drop the boost down to 12psi holdin 8psi to be safe?