Wait with the boosters till you're older, imho! You're 20, you should have tons of testosterone in your body to utilize maximum muscle growth... Get some solid sleep, change your training routine for building muscles.... and ..... EAT LIKE A HORSE!!! Quality food rich of Proteins... And don't be afraid of either carbs or fat!
Having problem getting your protein ratio up ? Well, some whey would be good a good investment..
If you do chose to go with the testoboosters anyway, I would recommend either Mass-FX or Hard-FX depending on your goals.. (Like pure bulk or some leaner gains).. Hard-FX contains DAA, which have been meantioned earlier in the thread), DAA is a solid natural testobooster.. I'm very fond of it..
AX added 7-MF , a natural AI, to help lowering the estrogen levels while also increasing testosterone from DAA and the other goodies as Fenugreek and Forskolin..
Regardless of which one you chose , if you even chose one, go with
1, don't go with a full stack if you never tried them before.. You don't know how your body will respond to the different things.. I mean, if you're a non-responder, it would just leave a big ass hole in your wallet!
Good luck mate and train hard!!