Dear Uncut4Big,
I am assuming you are referring to the viagra like effect of L-Arginine. Under normal circumstances, NO (produced from dietary L-arginine) binds to the enzyme guanylate cyclase, forming new cGMP. Increasing the amounts of L-arginine increases the amounts of NO formed. Thus, by enhancing NO formation, L-arginine supplements also increase cGMP levels, in a physiologic way. More L-arg. means more NO, means more cGMP and better erections, naturally. Concerning the amounts, while I do not endorse taking large unphysiologic amounts of individual amino acids, L-arg. seem pretty safe at dosages above the 1.5 gm you indicated. Some take 5 gm per dose with no side effects; this comes under discretionary experimentation of the individual. You can try various dosages over a period of time and observe the results (if any) than make a determination of the efficacy for you personally. One to six grams per day would be a starting place.
Supplementation is an art and science (a soft science at best). In the absence of a health professional specializing in supplements, you will have to experiment. I do know of individuals taking 5 gm/day with no negative effects. Let me know your results should you decide to try more L-arg. Hope that provides some insight.
Best regards,
Merlin