Hello Fibre,
High BP isn't what makes one look more vascular. Don't confuse high BP with the various poses which bring out the veins when holding your breath and flexing.
Both viagra and niacin are well known for helping bring out vascularity... and both products lower blood pressure levels. These products both allow the blood vessels to relax, and thereby enlarge, and the blood flow is not restricted. It is this process which actually makes ones vascularity increase. There are many vasodialators (this is what niacin and viagra do) on the market nowadays which profess to make ones vascularity more pronounced, I'd say it's hit and miss as to how effective they really are.
Keep in mind heat will always work. It's the body's natural method of staying cool. As the body heats up, the blood vessels naturally come closer to the surface to allow the circulating blood to radiate heat through the skin. So one of the things I do and recommend is to stay covered up and warm right up until time to go onstage. Keeping in mind a minute or two for final oil touch-up.
The wine thing doesn't actually work that well and as SB says, has been around forever. My first contest was 20 years ago and I was told then to drink a wine and sugar solution half an hour before going on stage. Can't say I really noticed much benefit.
You are certainly correct as regards the genetics, low BF and carbing up properly.
Best to you,
MaxRep