Kooks Custom Headers - 09-10 Charger/09-10 Challenger - 6.1L HEMI Exhaust Headers Based on the 6.1L SRT-8 originated motor, the Kooks Headers are the perfect mate for these 600+ horsepower monsters. Header primary size will be 1 7/8” stepped up to 2” with a 3 ˝” stamped merge collector. These headers were made with the perfect sized primaries, bases around the firing order of the motor, in order to yield power gains of over 20 horsepower over the leading competitor’s headers. Optional add-ons include true hand formed merge collectors for an added power gain, stainless steel turnouts to direct the exhaust gas and even primary extension kits.