Once back on the dyno, the C5 pumped out 338 hp and 348 lb-ft of torque. That's a gain of 25 hp and 24 lb-ft of torque at the wheels. Not bad for an exhaust swap and a cold air induction. Hank Jr. also leaned out the air-fuel ratio a little as it was running rich (12:1 range). At this point we figure our engine horsepower to be at around 398, and that's only seven shy of our goal.