and a new valve spring package with dampers to positively control valve action. Valve lift stayed at just over 0.400-inch with 1.5:1-ratio rocker arms. The tri-power equipped XS-code 389 was shipped with the Ram Air pan in the trunk, and the dealer had to fit it and cut out the underside of the hood scoop to make it functional. The XS-code 389 was still rated at 360 bhp at 5,200 rpm, same as the more common WS-coded Tri-Power 389, but performance was noticeably improved on acceleration runs. Pontiac engine production records report that 190 XS-code 389 engines were built during the 1966 model year. Whether all were installed in GTOs is unknown. None of Pontiac's Ram Air engines actually enjoyed any true ram air effect. The inlets were all well within the boundary layer that exists close to the surface, so all of these systems would more accurately be described as "outside air induction" systems, benefiting from the intake of cooler, and thus denser, outside air versus the comparatively hotter and less dense air under the car's hood. Ram Air (1967- mid year 1968) Simply called "Ram Air" by Pontiac it was the first in a series of engines available from Pontiac as regular production line options and officially called Ram Air. Hewing to GM's standing edict limiting engine size to 400 cu in for its midsize and smaller cars, the (underrated), the 400 cubic inch Ram Air V-8 was the most powerful and advanced option available in the 1967 GTO and Firebird. Its cast "670" heads had taller valve spring heights than the standard D-port heads, and the only 14-degree valve angle closed combustion chamber making these heads unique. It featured the "744" 301/313 camshaft, which offered more duration and overlap than the "HO". Along with the HO it also had Pontiac's famous cast-iron "headers", which were much better at reducing backpressure than the regular manifolds. The 670 heads were used until May 1967 when they were upgraded to become the "97" heads, which were then replaced late in the model year by the "997" heads which incorporated the upgrades of the "97" heads. Ram Air II (1968 1/2) The 1968 Ram Air II remained at 400 cu. in., again available only in the GTO and Firebird. It was factory rated at 366 hp at 5,400 RPM and 445 lbs.ft. of torque at 3,800 RPM in the GTO, and