Maybe other members can provide more information but going from 300~ to 1500 ng/dl should change something in your daily life. For me, going from 300 to 800-900~ with injectables, I can say I got much more energy, motivation, libido, no more ED, better recovery and endurance in the gym.
If you had 300ng/dl test before and you were asimptomatic, then the only difference you can feel is in the gym, you should recover faster than before and thus grow lean mass faster.
If you had 300ng/dl test before and you were asimptomatic, then the only difference you can feel is in the gym, you should recover faster than before and thus grow lean mass faster.