The 5.3 is gutless from idle till mid range rpm, where the power comes alive. The 5.4 has stump pulling power and torque from idle till mid range rpm, where it becomes gutless and asthmatic. For trailer towing, low end torque and throttle response, the 5.4 is better. For fuel economy and spirited revving power, and exhaust note, the 5.3 is better.