These Tri-Y design headers yield maximum power from off idle to 4500 RPM making them well suited for applications demanding maximum mid-range torque with maximum fuel economy. Every header is tuned with the proper tube size and length to eff icientlyremove all the exhaust from each cylinder reducing pumping losses for dramatic gains in horsepower and torque. Dougs headers are carefully developed on the vehicles they are intended to fit and are checked and rechecked numerous times during t he design and manufacturing process. Once you check the heavy-duty 1/2 to 5/8 thick machined and finished header flanges the smooth mandrel bent tubes and the attention paid to assembly youll want Dougs