Those "small modifications" that I can spot comparing the OP's pic with your linked pic of an HSB and others found online being -
1) the hull chine, so a different shape to at least the hull side
2) removal of the rubbing strake
3) different deck profile
4) different cockpit shape and profile
5) different radar mast
So different in fact, that it is not "the same boat", though it may serve a similar purpose. Definitely not a Fountain Executioner or any other similar USN HSB design in recent service unless it has been through a chop shop and become essentially something else.
There are some pics
here (treat the captions with caution) of a similar boat that looks more like a modified version of Joe's linked HSB. Perhaps that is what Joe had in mind and the OP's pic is of the latest version on a different hull.