Wastegate spring pressure can significantly impact your system's boost pressure. Without a boost controller, the spring pressure directly correlates to the boost pressure - for example, a 10-pound spring results in 10 PSI of boost. However, with a boost controller, you can effectively double the spring pressure to achieve around 20 PSI. So the general rule is to choose a spring pressure that is half of the maximum boost your engine will see. When reinstalling, make the diaphragm isn't pinched and confirm that the firing ring is seated onto the flange properly to prevent any issues with your turbo performance.