Hey everybody, so I haven't read a whole lot of the thread but noticed this last night on Giggles stream. The G-LOC is a little wonky in the Viper.   
So I'm just a normalish guy.  Been in the Air Force for 13 years, not especially athletic although not out of shape.  The last 2 years I've been an F-16 GIB.  I went to centerfuge with zero strain training.  The 9G profile is required to fly in the 16.  Take this for what its worth, but a dude who had just learned what a G strain was, then thrown into a centerfuge where I would do sustained 9G did not G-LOC.  I barely even lost vision.  Squeeze the butt, push out the stomach, and breathe right.     
Now after two years of lots of BFM flights, it's laughable how off the Viper G-LOC seems.  Also to the guy who said the feet are above my butt, at least in the backseat that is not the case.  Maybe if it was 6 foot 2ish and had the seat ran all the way down.  But I'm 5 foot 8ish on a good day, so I run the seat all the way up or until I can put a fist between the canopy and my helmet.     
I'm not an expert, so take what I say with a grain of salt.