Installed these JBA short headers on my '06 V6 as an addition to the Ford Racing Performance Pack and the improved performance was immediate. I feel a real increase in horsepower and torque throughout most of the power band but mostly at the low end and the exhaust note is now a much deeper growl, particularly at idle. Throttle response was also improved a little. A big improvement over the factory manifolds. The headers are high quality and were a perfect fit that bolted flat against the engine and have been problem free.