At your age, you still have a lot of growing to do. Introducing test, which converts to estrogen, can possibly close your growth plates early. You are probably done gorwing taller, but long bones, like the clavicles are still slowly growing. The clavicles will determine how wide your shoulders are. If I were you. Also, the endocrine system is very fragile, especially at your age. If you start messing with it now, it may effect your ability to produce a healthy amount of natural test in the future. I know a kid in my gym that is your age. He is on a similar path, competing in the teen division MP shows. He is doing well, but he texted me the other day, asking for HCG because he "didn't recover from his contest prep and can't get a hard on". It's a shame and it doesn't have to be that way. I would wait to use streroids. At 18 ye 160 lbs, you have more natural test in your body than you EVER will again and you can make some amazing gains naturally with the right plan. You mentioned that you have a good work ethic. That's important because if you want to take your physique to the next level, you are going to need to work. I'm not just talking about the gym. We all love to train and grind in the weight room. I'm talking about the dedication it takes to eat 7 times a day and never miss a meal, for a year straight. And to learn how to change those meals to fit your goals.

Even if you do use gear, you will not gain 20 lbs of muscle in 12 wks. You will gain scale weight, but a lot of it is going to be water and fat. So now that you know my postion on this topic, I'm not going to turn you away. I don't want to risk you getting some bad advice that may mess you up. If you still decide that you want to use steroids, I would suggest you use nothing more than anavar for the next couple of years. I would take about 40mg ED for a 6 wk cycle plus a solid PCT after. It would probably be more suited for your goals anyway. You aren't going to have to worry about conversion to estrogen.  You aren't going to gain lots of water that will blur your lines. What you gain will be more "real". The gains would not be as big as with test, but it is a much safer option. Do yourself a favor and read up on anavar and read up on PCT, if you decide to move forward with steroids. If you decide to wait and see what you can do without them, feel free to ask for help with any questions you have about dieting and training. Either way bro, stick around.