If your recipe calls for pressure canning it must be because there is not enough acid or sugar in the salsa. Pressure canning cooks at much higher temps than boiling water. That is needed to kill bacteria that could grow later on like botulism.
Don't listen to those other poster who say you can interchange the methods because you can't. There is a reason why you need a pressure canner.
Why risk getting anyone sick. Follow the recipe.
