Couple of pro-tips here...
- Never use research grade, ALWAYS use pharma grade when going with exogenous T3
- In reality, unless diet/training/lifestyle/dosing is severely out of whack, there will be no significant skeletal muscle atrophy even for natural individuals
- When using supraphysiological amounts of AAS, there will certainly be no atrophy
- Although exogenous T3 increases protein synthesis rates, it increases protein breakdown to a greater degree meaning it is net catabolic
- T3 is NOT to be seen as a "fat burner"
Now, my advice is that T3 should be respected and understood before blindly adding it to a hormone stack. As I said above, it should not be seen as a fat burner, as this is a severe oversimplification of how it works.
When you go beyond 25mcgs/day (estimate), you enter hyperthyroid territory. Please understand what hypothyroidism is and the potential sides that come along with it.
Exogenous thyriod does have a nice synergy with beta two agonist compounds as they may increase both the density and sensitivity of beta two type receptors in fat tissues.