L Arginine is often the key ingredient of most muscle building, penis enlargement, or anything enlargement (for that matter) supplements. I love the stuff, but I have not as yet tried it in this context, although I have certainly considered it (especially with massage). Purveyors of penis traction devices will often also offer an L Arginine based penis enlargement supplement to bolster the effects of the traction devices. So I've often wondered why I haven't seen sellers of breast suction devices (Noogleberry - Kangzhu)  are not also selling an L Arginine based solution as well (hey, don't steal my idea).

One a number of people really like is the L Arginine Ornithine supplement combo under the Vitamin Shoppe brand (I'm guessing it may be because the Arginine portion is not HCI but free form). GNC used to sell an awesome micronized L Arginine powder in a tub, but discontinued that (it may have been a little too intense).

L Arginine is not HGH, but it's often in HGH enhancer supplements that aim to stimulate your own natural HGH production.

As for a supplement that is reported to actually increase serum HGH (in active men anyway), that nod goes to Macuna Pruriens (Velvet Bean).

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3738483/

There's a higher risk for increased hyperkalemia in older males with diabetic risk, this risk is higher when with amino acids L-arginine and L-lysine (intravenous delivery) as listed in this study below. Although oral (dietary) amino acids weren't listed as part of this study....there's an apparent increased risk when you add spironolactone. Just a word to the wise or heads up to those on spiro and considering aminos. I don't know if this info has been pointed out in TG forums or not?, none the less I hope it helps.

amino acids lysine and arginine have been shown to enter muscle cells in exchange for potassium and lead to hyperkalemia through a shift of potassium from the intracellular to the extracellular space.

 
Acute hyperkalemia associated with intravenous epsilon-aminocaproic acid therapy.

https://www.ncbi.nlm.nih.gov/m/pubmed/10196024/