Drag racing champion Doug Thorley is committed to building the highest quality and best performing headers for cars and trucks. Doug Thorley headers can result in an increase in horsepower, an increase in fuel economy and better overall engine efficiency. It is available in a 4-tube-into-1 collector design, and a new tri-Y design especially suited for today's low compression street engines. Features an industrial chrome finish for corrosion resistance, extra heavy wall 14 gauge steel tubing for durability, precision flamecut 3/8" flanges to prevent warpage, perfect fit for leak-free operation. Most of the headers are legal in California.