19# injectors are good to around the 300 hp mark, and if you are not going to do much to your car, you don't need anything bigger.
Therefore a MAF and injectors is a waste of money. To get your car over 300 hp, and NEED bigger injectors, you will have to do quite a bit to it... heads, cam, intake. If you don't plan these things, don't waste your dough.
Get a cold air intake, and aftermarket exhaust from the headers to the tailpipes, and that will be a nice foundation for a mild car.
Maybe spend a few bux to get some subframe connectors installed, and that will give you the solid foundation for handling mods, as well as beef up your chassis for higher horsepower in the future.
Edit: I forgot to mention gears. For a mild vehicle, those will give you the most gain you'll feel at the seat of your pants. Sub connectors, exhaust, and gears... these are the places we all should start. Then either enjoy the car as is, or build upon that foundation.