Best Retainable Gains?

my friends using my account because he doesnt have one yet.

I'm planning on doing a tbol cycle some time within the next few months. From reading around i get the impression on tbol a person can gain upto 15 pounds and keep naturally 5-7 of these with proper diet and pct. I also bought some anavar and after seeing a friends results it barely looks like hes lost any size whatsoever.

As a goal of achieving retainable gains, am i better to do one cycle at a time, or stack the tbol with the anavar?

Stats??

age
weight
height
lifting experience
BF

Stats and oral only cycles blow.