No boost jets from the factory. A boost jet restricts the vacuum for the stock wastegates. This causes them to stay closed longer and increases your boost. Typical gain leaves a stock Z boosting around 14 lbs. From the factory the Z boosts around 7 psi. Since the hoses are not restricted from the factory the wastegate sees vacuum sooner and opens the wastegate sooner lowering maximum boost.
If he has boost jets in the lines still that's why he's hitting 14 lbs with the EBC off. You should remove any boost jets and factory wastegate control when installing a boost controller. The idea is to have the boost controller handle all of the turbo operation. When the boost controller is off nothing else should control the turbo except the wastegate springs. These springs will hold 5-6 lbs before opening the wastegate.
