I am probably chiminng in late ( as always) but I love my pre workout, C4.
I can tell huge difference if I miss a dose. I am an old fart and it helps me get going.
If I take 2 or 3 scoops I can, as a recent post said, see noise. LOL
When a person reaches beyond the limits of their ability; they shall they make progress. There is no other way.