If you are looking for more horsepower for getting around, or just want to hear that ‘big block’ purr, then you should take a look at Kook’s Custom Headers. Offered in 1-3/4 or 1-7/8ths inch primaries and for the 5.4 and 6.2-liter engines, Kooks boasts up to a 40 horsepower gain to the rear wheels.