I was tuning my Z saturday night with wideband 02 sensors. I had to put drag tires or car would brake traction easy. I went up and down the highway busting it 22 psi of boost and the turbos hold 22 psi rock solid all the way to redline. It was a cold night and I used water injection on cheap 91 octane fuel. A/F was showing maximum rich at 11.2:1 I heard light preignition at 20 psi. It sorprised me because it should not ping with water injection at least. I richened a/f with safc up to 10.5:1 and preignition went away.
I will be running at the 1/4 mile track on sunday. With race fuel I will boost it up to 25 psi.