It won't make the fruit grow bigger - the plants need the leaves to photosynthesise to make the raw materials to build tomatoes. However, they may ripen better once they have grown if you remove some leaves (to let the sun get at the fruits perhaps). I usually take any off that are looking the worse for wear and generaly thin the leaves out. I confess that I usually find that they are sideshoots I missed earlier in the season.
We shared our first ripe tomato last week. Not exactly a glut yet!

PS What are heirloom tomatoes?