Test 1: This is as close to bone stock as we could get with an electric water pump in lieu of the accessory drive and a set of JBA-coated 1-7/8-inch headers with a 3-inch exhaust leading to Flowmaster mufflers.
Test 2: The only change was to add 2 degrees of timing near the peak power rpm since total timing at WOT was only 23 degrees BTDC, making the new total 25 degrees.
Test 3: This test bumped the peak timing to 27 degrees total with a minimal gain.
Test 4: At WOT, GM runs its engines very rich to protect the catalytic converters from overheating. We leaned the air/fuel ratio from 11.2:1 to 12.5:1, which pushed the torque up to 522 and peak horsepower to 518.