You are experiencing the "classic" Thrasher 92 boost spike.
The spike is the result of Thrashers "way of doing things". Mike Savino of Turbobuicks.com printed out the plot of the wastegate duty cycle programmed into thrasher chips a few years ago and the solenoid stays wide open while the gas is floored, then starts cycling to control boost (but not until after the spike). This is part of a thrashers "quick spool" feature.
At least it spikes when the load is low on the engine (timing is probably still retarded at this point, too).
Yes its there, you probably won't see much knock asscociated with it, so don't worry too much about it (as long as the boost it drops back too is low enough not to knock)
