Though the ’66 389 Tri-Power had a new intake manifold with a larger center carburetor, the engine was not re-rated from ’65, though it likely made a little more power. The hotter-cammed Ram Air XS-coded engine was also rated at 360 hp at 5,200 rpm with 424 ft-lb of torque at 3,600, like the regular one. The reason is that Pontiac wanted to keep in compliance with GM’s new 10-pounds-per-horsepower minimum ruling. A higher rating would put the power-to-weight ratio below that level and cause problems for the Division. As was the case in the past, a heavy-duty three-speed manual was standard, with four-speed manual or two-speed automatic transmissions available as optional equipment.