My painter messed mine up using a Graphix Express stencil as well, but it was a compounded problem. First, he sprayed the whole hood black, and went to apply the stencil several hours afterward (Strike 1: he didn't get the clue that the TuTone was added AFTER the body color, and the paint was barely even dry). Then, he misread the instructions and placed it with the leading edge of the stencil lined up with the leading edge of the 'pretty part' of the hood sheet metal - without the nose trim piece in-place (Strike 2: couldn't follow the simple instructions printed on the stencil itself). Finally, he didn't bother to find the side-to-side centerline of the hood, and put it on too far to the passenger side... but it's already stuck down at this point, on barely ready-to-go paint, so the template's either going to pull up the hood paint or become stretched and unuseable during the process... or both (Strike 3: still can't follow instructions, doesn't have 'the eye' for such things, and can't or won't measure things properly) - the body guy said, "Hey - it looks good to me." Yeah... wow.
The passenger side looked OK - maybe a little too far over, not horrible... maybe around a half inch or so - I can live with that. The driver side on the other hand, looks like a lot of those jobs where the painter just decides to eyeball it and winds up cutting it too close to the raised area. Oh. My. Gawd. I almost lost it.
At that point I took matters into my own hands... literally (I've striped about a dozen cars in my time with tape stripes and paint... I'm 'pretty good' at it... not an expert, though). I managed to cut away the part of the stencil on the driver side without pulling up the hood paint and hand-striped the whole driver side myself. After measuring against the passenger side, I was happy with what I wound up with, only to find out that he had the body guy (who had said earlier that it looked good to him) mask off a 'negative' image of the stencil to protect the black hood paint while he shot the body color - he basically pulled up everything I'd done, which looking closer now, I can definitely see where he'd not gotten some of curves as fluid as I had.
I'm thinking that based on how much I had to add to the driver side, and it still came out pretty close (aside from being too far back and glossy), I think the Graphix Express stencil might actually just be 'close,' as 7173Vert mentioned... but, it's better than nothing.