Re:TREN ACE only cycle
I know people who have run Tren alone and they look great.
I also know those who have run Tren at a higher dose than Test and haven't had issues with libido or recovery, but then others who have.
Point being, its all subjective. You have to make an informed decision and accept the consequences.
As for cardio and tren, not really a problem. A little more out of breath, but nothing excessive. Mind you I was only using a very low dose, but it worked wonders for me.