Rockstar, usually the diet version, but I drink regular if I have to. It's all about the vitamin B. When I worked on factory trawlers with several Japanese crew members (Japanese company was %50 owner) we used to get cases of small brown bottles/Vials filled with what the Japanese called "Hubba Hubba juice" It was basically pure vitamin B in all it's forms. One of those 4oz bottles would make your head start tingling and keep you going for hours. We worked 12hrs on 6hrs off for weeks at a time drinking those things.
2 x Xeon e5520 | Asus Z8NA-D6C
12 GB G.Skill DDR3 | Radeon 5850
Corsair 128GB SSD | WD Black 1TB HDD