However, for me it has to be the RR Pegasus/Harrier GR3. 21,000 lbs thrust (wet) in an airframe whose basic zero fuel weight was 12,500 lbs. The acceleration when the jet was light was truly eye watering. The engine was tough and the abuse it took, especially during deployed Field Ops, was staggering but it never let me down and hauled me out of more close shaves than I care to remember