The 1969 Pontiac GTO Ram Air III and Ram Air IV configurations represent the same basic engine in significantly different states of tune, and the distinction is important for a buyer.

The Ram Air III: 366 horsepower, round exhaust ports on the cylinder heads, hydraulic lifter camshaft. Tractable, strong, easy to live with. The Ram Air III is the engine that most 1969 GTO buyers ordered.

The Ram Air IV: 370 horsepower officially, but the factory rating was deliberately conservative. Oval exhaust ports on round-port cylinder heads that flow significantly more than the Ram Air III heads. Solid lifter camshaft with aggressive timing. The Ram Air IV requires more maintenance and has a rougher idle, but the top-end performance is substantially greater.

The Ram Air IV is the car for someone who wants the GTO experience at its most intense.