soontobeboost

so i got tuned today and on the dyno my car would go to 8psi and then slowly drop. im running a 10 lbs wastegate spring with a tial wastegate. i pressureized the system and it held with no leaks. checked all the cuplers for cracks or holes but nothing was found.
would the pressure sytem tester tell me if my wastgate gasket is leaking? and im missing a stud from my turbo to manifold. could that cause anyhitng?like not enough exhaust to keep the turbo spoolin?