do LS1's stay in closed loop at wide open throttle? when these engines first came out, i remember reading that somewhere.

 

Nope. Open-loop at WOT. There's a PE table (Power Enrichment) that the PCM references to get a desired AFR (11.7 or so from factory), which is used along with the data from the closed-loop (cruise) tables (VE-Volumetric Efficiency, LTFTs-Long Term Fuel Trims, etc.). That is why adding a little spark advance @ WOT to get 27~28* and leaning out your WOT AFR to 12.8-13.0 can get you anywhere from 10-20hp over the stock tune.