From their inception in the 1950s until the early 1970s, Pontiac engines were known for their performance. The largest engine was a massive 455 cubic inch (7456 cc) V8 that was available in most of their mid-size, full-size and sports car models. At the height of the horsepower era, Pontiac engines reached a powerful 390 rated horsepower (SAE gross), though other engines achieved considerably higher outputs in actuality. Federal emissions laws eventually brought the horsepower era to a close and resulted in a steady decline for Pontiac's engines. One holdout to this industry-wide slide was the Super Duty 455 engine of 1973–1974. Available only in the Firebird Formula and Trans Am models, this was rated at net initially but after having issues passing EPA emissions tests, the camshaft was changed to the old RA III cam and with the change, came a net rating. The engine was the pinnacle of Pontiac engine development and was a very strong performer that included a few race-specific features, such as provisions for dry-sump oiling. This engine and its legacy drive the SD Trans Ams and Formulas as one of the more, if not the most, desirable Pontiacs ever produced.