so i may have a similar problem. I have a 1990 gtst with a couple upgrades (greddy profec bspec 2 turbo programmer, apexi air controller/power commander, turbokentiks turbo, intercooler and full 3in exhaust). I had the same problem of my turbo spiking from 14psi-20ish with my engine rpms being governed out at about 5000 because of my blow off valve releasing my pressure. I went to a jdm shop and the guy told me that even though i had an upgraded turbo, turbo programmer, air programmer and power commander since i set my turbo programmer over 12 psi and i dont have my ecu chipped it locked it self at the 20psi it was set at once upon a time. I was wondering if anyone has heard of this happening? he said my only options were taking a chance with him plugging in another ecu and removing the battery cable while the car is running then plugging mine back in hoping it will continue at the settings of his or i can buy a new ecu then drive it to Calgary(300km away) to get it dyno tuned which in all would set me back about $1200cnd. Anybody know if i have any other options?