If your car is an 89 or 90, it has a 55mm maf unless someone else has already changed it. Some of the 91s had 55mm as well and sometime in 91, they switched to 70mm. The 73mm is a good bit bigger than the 55mm and is slightly bigger than the 70mm. The stock throttle body however is 60mm. Anytime you can increase airflow, you will gain some horsepower.
If you changed mafs, you would not need to change injectors as this mafs is set up for the stock 30# injectors. Removing the air silencer will help as well, if you haven't already done that. I see you have a 92, so you should have a 70mm maf on it.