What engines can be swapped into a 2003 Cadillac CTS?

The 2003 Cadillac CTS is primarily compatible with GM's 3.2L V6 engine, but enthusiasts often consider swapping in the more powerful 3.6L V6 from later CTS models or the 5.7L LS1 V8 from the Corvette for enhanced performance. Additionally, modifications can allow for the installation of other GM engines, such as the 6.0L LS2 V8. However, any engine swap may require significant modifications to the transmission, wiring, and exhaust systems. Always check local regulations and compatibility before proceeding with an engine swap.