The bars are 5/8" with a .125" wall. So fairly heavy duty in terms of tubing. Using the formula's in Staniforths books, I should be ok in terms of material size, my only concern with them is how long they will last (5k miles, 50k miles etc). Even if they only survive 5k miles I'll be happy. The other thing too is sizing, from the notes that I've gathered, 5/8" should be fine for the rear bar, but the front may require a slightly larger bar (though for what I'll be using the car for, I doubt it would notice a big difference).
And, in terms of bending them, bending them by hand didnt work at all. I had to break out the 10 ton press.