How come horsepower tv gained a very small amount of hp off a 70mm TB on a 97 stang?

[96_4.6]

Oh I undertsand that its just the first dyno results I've seen on a 96-98 gt with a 70mm tb. Everyone says you will lose horsepower blah blah blah but what if you dont? Until someone makes 5 runs bone stock and 5 runs with a bigger tb on our non pi head cars we wont know cause like i said I can only spend very little money on parts cause I'm young and I'm not one of those kids were the parents give them whatever they want cause were not rich so I'm just lookin for a decent $100-$120 mod and that fits......