If the car is speed density then you need to convert over to mass air.
A small supercharger will not make your car feel any different than it is now powerwise when it is not under boost. When the load and or rpms increase the blower will make boost and you will crap your pants the first couple of times until you get used to it. If your car is relatively stock and you bolt on a small blower you will not need to change anything except the fuel pump. If you modify the car more after that you might need injectors and fuel system stuff but for a stock car you will need nothing. Pretty much every small blower kit includes an fmu so fuel will not be an issue if you have even a moderately sized intank pump like a 190.
Although it is a very arguable subject, I will agree to disagree with 90mustangGT. I do not think that H/C/I would give you as much TQ or HP as even the smallest blower. It would take a lot of stuff to make an extra 75hp with bolt on NA parts. It can be done but for twice the money. Not that what he said could not be true, but rather, in this instance it would be unrealistic.