hmmm maybe turn your boost down to 12psi and see if it does it
i would think that you are maybe detonating and then the ecu is retarding timing
turn down the boost and have a look then
also those funky lightshow gauges... that's pretty much all they are... they work like this
..... i think i'm rich... ah now i'm lean... i think i'm in the middle now... oooh rich again
it's not accurate... just a guestimate
i threw mine out