I think the stock front bar is .875 or .937, I forget. I any case, it is under an inch.
What you may find is that at the limits of traction, your car will tend to be loose in the rear with the stock sway bars installed. Try it and see how you like it. If you don't like it that way, you can either remove the rear bar or step up the size of the front bar to bring things back in line.