Tren ace is better for cutting cycles and taking advantage of its anti-catabol abilities, this is what this drug is most famous for, being able to keep your muscle while cutting and doing cardio, maybe even adding a little muscle while cutting. Its actually not that good of a mass builder because of how it boosts your metabolism and there are better options when building mass. If you are looking for a good lean mass cycle, then I would use tren ace to have it help keep bodyfat off and add some lean mass, but you would have to add test, which is a great combo for lean gains.