The 300 is a torque engine, so the high rpm breathing you get from long tube headers is probably pretty much wasted unless you are modifying the internals a bunch for more rpms I would go with the fuely exhaust manifolds, that long 6 header is hard to seal and noisy as hell, no matter what mufflers you runCherokee Six 300 — More powerful version with 300 hp Lycoming IO540K sixcylinder horizontallyopposed aircooled engine, driving a twoblade constantspeed propeller available also has a floatplane, on the Edo 3430 floats and with propeller of 7 ft 0 in (213 m) diameter Two oil coolers and alternate air source (automatic with manual Ford 300 6 cylinder headers