Since no one cared to provide any straight up answers, it means you take the top end (heads, lower intake manifold, supercharger, fuel rail and injectors, throttle body, etc.) off a supercharged 3800 and swap it onto your N/A GT. It's the cheapest way to "heavily" mod a stock N/A 3.8. A whole kit runs about $500 and then you need to either buy or rent a tuner. As well as all new gaskets.