one of the main benefits to taking T3 specially while dieting down/cutting , even at a replacement dosage, is that the metabolism variable becomes ‘fixed’.
a fixed variable is a very useful tool while dieting down.. having to manipulate your calories, your carbs, your cardio, etc.. all the damn time because your metabolism keeps fighting against you can be a pain. so even a 25mcg replacement dosage of T3 at least helps keep metabolic variables more fixed.
also your T4/t3 natty production is likely slightly suppressed from the tren run .
note – for recomp and bulking/hypertrophy I generally prefer T4 over T3