Back to the original Denny Conn's Bourbon Vanilla Imperial Porter from http://www.brew365.com/beer_dennys_bourbon_vanilla_porter.php I will scale back the bourbon to about 1 cup for 5 gallons. I did that a few years ago on a bourbon barrel recipe after extensive testing (woo hoo!) on 4 oz test sized cups, and it came out just the way I wanted it. Not sure what bourbon (or whiskey) to use. Makers Mark is very good.