what will fit??

Hey got some questions on some performance parts to try and loosen up the car! Uhh first, will the intakes from a 300zx fit on my j30t? Headers? ect. also is it really a fact that if you switch the ecu you gain 32 hp? I dont see how that is possible when the 300 non tt only makes 222hp. does it affect the gas mileage. lol kinda a lot but hey its good to know.

an accurate response would be nice, it would clear up some bs floatin around