I just got asked that question today by a client of mine. In good shape, doesn't have test, wanted to take tren E only to hold onto muscle while dieting to even lower bodyfat. I advised against it due to his relative newbie status with gear, but I have run tren E alone with good results. The only reason I don't anymore is b/c I cannot handle the sides that come with the dose I would need to see good results, so I have to stack it. Tren E past 500-600mg/week and my pumps are so bad I can never get halfway through a workout by week 4 so I keep it lower and throw in other gear. I would advise against tren E only, run test with it, preferably test E so the ester length matches, but tren E or tren A by themselves can and have been done by many, with varying degrees of sides and success. It's really up to you.