I was reading that Sustanon is not good at all for keeping the gains. I am currently on a 10 week cycle on week 4. I read that deca-durabolin is great for keeping gains so I want to add it in on this cycle. What dosage should I take and how should I fit it in on this cycle. should I rev it please reply because I have to order this weekend to get it here and if there is another AS that would be a better fit?

currently taking 500mgs of Sustanon a week
24 years old
240 pounds
1st cycle
5' 11''
friend also on cycle
35 years old
235
1st cycle
6' 0''