Well for starters, with deca only cycles you are asking for impotence. It is a common side effect for a lot of people (not me thankfully). Testosterone (you know, the male sex hormone) helps to avoid this. Adding Test with orals is advised because orals for the most part are hard on your liver. Test (once again the naturally occuring male sex hormone) will give you great gains, feelings of well-being, and good strength, without having to run a fuck-ton of orals. Now if I really have to I will go look up a bunch of studies for you but I really don't feel like it right now. The point is, Test is IMO the BEST base for any cycle. Look at the thread about the one steroid you cannot live without, and see what % answer TEST!