I can feel it coming while I'm injecting as it's a tingling in the chest and throat followed by a chemical taste in the mouth. It's then a good solid minute of a 500lb gorilla sitting on my chest with his paw wrapped around my neck squeezing coughs out of me. It's not pleasant, but I wouldn't stop taking tren because of it. I just try to finish the inject before it hits me. I have had it come on with a needle still wiggling around in my delt, but nothing bad came of it.
My .02c