i dont have clinical evidence but i have been in the game for a LONG time(16yrs). and have 7 friends(off the top of my head) that MUST use viagra when they do have sex(be it not often that they want to when not cycling).. these are not old guys either..
i am just tryin to help u out man, no need to get defensive
i am just tryin to help u out man, no need to get defensive