That coach is bonkers… likely doesn’t know what they are doing and looking to force temporary gains fast to make you happy and generate before/after marketing materials. These are your early cycles, and you are getting more from just 400mg of test than you are able to take advantage of. Anything you add is not going to cause any additional permanent muscle gain (said otherwise, the more shit you add, the more strength, water retention, glycogen retention, and negative side effects you will get… which all subside, and the actual amount of actual muscle gains are going to be the same). If you want to feel like you are on a shit ton of gear, then take more gear. If permanent muscle growth is your goal, then stay at 400mg test and start questioning what your coach’s nutrition and protocols are. In reality, if you move from 400mg to 500mg test, this is the breaking point for more advanced bodybuilders where high estrogenic side effects occur. You’ll then need an AI or a SERM, which if you don’t know what you are doing with those, will likely crash your estrogen or leave you with gyno… both will be distracting and take away energy from what is important and that is staying consistent with your food intake and lifting hard every damn session. There are two things you can control, maximum protein synthesis and time spend in a maximum protein synthesis state. At 400mg test your protein synthesis is probably 90-95% maximal IF your nutrition and training are setup perfectly for you. The more shit you find to distract yourself with, the less consistent you will be, which means the less time spend in a maximum protein synthesis state, and the less optimal outcomes you’ll get.
Anyway, my 2C. Drop the trash, leverage 400mg (which is a good amount of gear for someone at your experience) and dig into your food intake and training protocol. Someone with good nutrition and training will get more out of 400mg test than someone on 1000+ grams of gear but with bullshit nutrition and training.