the sniffer is usually off .5-1 point AFR from what a WIDEBAND would read.

IMO, its DANGEROUS to run that much boost on pump gas, Built motor or not. 20psi is about the threshold on pump gas. but hey, not my call lol. 1 detonation will kill those pistons at that boost level.

If i were you, id get it tuned on the dyno ( i assume you street tuned this) and be conservative with it an see what its doing.

The car was prob heatsoaking, thats why there wasnt a big change between 2psi.

put it this way, Nyteryders made 400whp on pump gas at 19psi. On race gas, at 23psi, he only made 444whp. an hes beating EVERYONE right now.

you sir have a fast car, congrats!