yohimbine hcl.
trust me on this bro, you'll be rock hard, you'll last all night, you'll cum like a fucking champion.
plus it kinda makes you feel good, like kinda slightly drunk.
arginine doesn't do shit, i've heard good things about horny goat weed but that's just for libido... yohimbine isn't going to make you horny (at least it didn't me) in fact i really didn't notice any difference until it was time to do the deed, seriously i'm a young guy and i was fucking surprised, plus after about 5-10 min break you are ready to again and again. and again.