Welcome. As for modifications to Nissan's KA24DE 2.4L DOHC I4 engine, as used in the Nissan Hardbody pick up truck, I would recommend looking into what people do with the Nissan 240SX sportscar as it uses the same engine (early models from 1989-1990 used the KA24E, a SOHC variant of the engine) and has a massive aftermarket. The 240SX is extremely popular with drifters because it's cheap, plentiful, and rear wheel drive. There is a LOT you can do with that engine. However I will also point out the SR20DET engine is a popular swap because it's what the car used in Japan. http://www.youtube.com/watch?v=Yy2cYmtRHfY