You CAN run 600whp on a stock ECU, sure. You can run E85 on stock ECU (without flex fuel), sure. But you CAN'T have a MAP sensor reading 3.5bars of boost and have active boost correction. You can't have flat foot shift, you can't have ignition-retarding launch control, you can't have wideband O2 targets. You can't have closed loop boost targets using the ECU itself.