The whole packet isn't going to "ruin" you beer, but it will be out of style. As stated, Irish Stouts are typically more lightly carbonated than typical ales. Use the 2.5-3.0 oz to keep it in the style guidelines, and sprinkle the rest on a breakfast grapefruit or corn flakes!
Primary #1 - Midnight Ryeder (Midnight Wheat and Rye)
Primary #2 - Florida Weiss
Primary #3 - Kane-DOH APA (Honey Citra APA)
Secondary #1 - Downtown Flanders Brown (brewed August 2012)
Keg #1 - Raspberry Florida Weiss
Keg #2 - Cinnamon Raisin Cider
Keg #3 - NONE!
Bottled - NONE!