How do you upgrade 1975 Pontiac 455 horsepower?

To upgrade the horsepower of a 1975 Pontiac 455, consider installing a performance intake manifold and carburetor to improve airflow and fuel delivery. Upgrading the exhaust system with high-performance headers and mufflers can enhance exhaust flow and reduce back pressure. Additionally, tuning the ignition system and possibly installing a higher-performance camshaft can further increase horsepower. Finally, ensure the engine is in good condition and consider balancing and blue-printing for optimal performance.