I don't think you'll go any faster, at least not for long.
On a 14T sprocket you'll be turning 7600rpm at 70mph. (on stock gears you are turning 7100).
So, you'll have lots of torque there so you'll be able to hang on to that speed a little better in the wind and hills.
However, coax her up to 80mph and she'll be turning 8700rpm.
For how long????
You could say the stock sprockets are kind of self-limiting in 5th gear. Unless you're going downhill with a stiff tailwind you'll never hurt the engine by overspeeding.
see my charts for stock sprockets and 16-tooth mod near the bottom of this page:
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