whenever I used tren for precontest in years past, I felt like I was going to die when doing cardio. It always happened when I started using tren. Some other guys at my gym experience the same thing.
As far as to why transdermal over injections, sometimes in certain careers it would be a lot easier. When you are at work for 2 to 3 days at a time it makes injecting more difficult, and if you were to get caught with a dart you would be in the unemployment line. It would be a lot easier to have a squirt bottle in your shave bag and would not raise any eye brows if someone went through your bag trying to prank you. Lots of jokes get played at the fire dept