• Remove the non-turbo engine and transmission.
• Install the twin-turbo engine and transmission.
• Install the necessary turbocharger components, such as the turbochargers, intercoolers, and piping.
• Modify the fuel system to accommodate the increased fuel flow.
• Modify the exhaust system to accommodate the turbochargers.
• Install the necessary engine management components, such as the ECU, fuel injectors, and sensors.
• Tune the engine to ensure that it is running properly and safely.
In addition to the cost of the parts, you'll also need to factor in the cost of labor for this conversion. If you're not comfortable performing this work yourself, you'll need to hire a qualified mechanic to do it for you. This can add significantly to the cost of the conversion. Before deciding whether or not to convert your Mitsubishi GTO non-turbo 1990 to a twin-turbo, it's important to weigh the costs and benefits of doing so. If you're looking for a significant increase in performance, then a twin-turbo conversion may be worth the investment. However, if you're on a tight budget or aren't comfortable with complex mechanical work, then you may want to consider other options.