It may only read 10psi even if you are really boosting well over 14 or 15psi. Before I installed my SPI Boost Gauge I thought I was running about 12psi (judging from the stock gauge), but after installing the new gauge, I was actually pushing ~15psi.
Generally .035 tips will give about 15-16psi...but all cars are different.
So you should get an aftermarket gauge just to be sure of the boost.