IMO 20 weeks is way too long. If you are looking to bulk, as you say, mast is not your best choice. It is a great cutting compound for those with already low bf.
wk 1-14 test cyp
wk 1-12 EQ
wk 1-4 dbol
Yes, there will be bloat, especially in the beginning, but if you want mass, this is a killer cycle. Eat clean and a lot.