When I was on about 800 mg/wk of tren I rarely experienced any sides but one day I had pressure on my chest for a few days. Kind of felt like if a 5 lb plate was resting on my chest. By the third day I was kind of scared, and I searched around and noticed it was a relatively common effect but couldn't find the cause. Blood pressure was always around 130/65 and hematocrit was fine. Lipids were probably out of whack from tren, but that didn't really explain it so I kind of played around with the dose and noticed that the pressure was pretty much dose-dependent and then eventually I just got off it.