Well, you could either adjust the wastegate rod or completely disconnect the boost line from it. The latter will allow the turbo to build as much boost as it wants/is capable of. 5 psi does sound a little low. Check for boost leaks on the intake side first, if you suspect a boost hose leaking, a little hairspray on the inside can do wonders you've just got to be quick about it. Out of curiousity, do you know what your IP timing is set at? Have you turned the fuel up at all? Both of those factors can affect boost as well.