boost spike and knock retard

[grandnat86]

ever since i've had this car it's had boost spike problems, now that i have alky i try and run about 20 psi, it will first spike to like 24 then go to 19 and steady at 20-21. another problem thats developed lately that happened twice is when i'm on the highway downshifting to third at wot the motor audibly detonates and the scanmaster shows 10 degrees, the car runs awesome besides that intermittent knock, it's so random and it runs fine at wot 1st and second, could the boost spike be the problem, the car never shows knock at wot except those two times on the highway, i just don't want to blow a headgasket if theres an easy fix, o2 mv are usually 760 at wot in third

 

["Turbo-T"]

O2's should be nothing less than 780 at WOT in third.

 

[TurboMonte 2]

I don't know where you're set now, but perhaps you need your alky to "come-on" several #'s sooner to eliminate your apparent transitional knock...