Cocktail recipes need to be tweaked to make room for our local overly sour limes. Make room in the recipe for some sugar syrup to balance the sourness.
Another way to counter the sourness without altering the 'original recipe' is to make the syrup 2:1 water.
But for tequila recipes which originally doesn't call for sugar (as per iba) - highly recommended to put some syrup, if you don't want to see crumpled faces.
Iba postponed until further notice. :p