How do you replace a GA15DE with a SR20DE?

To replace a GA15DE with an SR20DE engine, first, ensure that you have all necessary tools and parts, including engine mounts, wiring harness, and ECU compatible with the SR20DE. Begin by draining fluids and disconnecting the battery, then remove the GA15DE along with its components such as the transmission and exhaust manifold. Install the SR20DE engine, ensuring proper alignment with the mounts and connections to the transmission. Finally, rewire any necessary connections, install the ECU, and check fluid levels before starting the engine.