You can see your commanded boost level in your logs, It's labeled TCBP_DSD(psi). That's most likely a boost spike. If you're tuned to 15psi, the 19psi spike is the highest I've seen. Boost spikes are fickle in the turbo world, they are seen as bad by some and good by others. Some tuners allow them to help with a mid-range RPM surge. It can make the engine feel more responsive and powerful in the mid-range. If you open a wastegate right as the boost spikes, the gate's latency to open makes it too late. But if you open it too soon, you can increase turbo lag. A wastegate needs to be given time to “catch” the boost curve. To eliminate a boost spike, the wastegate must begin to open before the target boost by a certain amount of time depending on the turbo system. If the wastegate begins to open at the target boost, a boost spike will occur as the wastegate will need some time to open to the right valve height to divert enough exhaust gas to maintain the desired boost level.
