Set sous vide machine to 74C/165F.
In a small bowl combine chili powder, paprika, cumin, brown sugar, pepper, salt and cayenne pepper.
Lightly season the pork shoulder with seasoning, and set aside the rest of the seasoning for later. Put the pork shoulder in a sous vide bag, and remove the air through a vacuum sealer or the displacement method. Drop the bag in the bath for 24 hours.
Remove bag from bath. Take pork butt out of the bag and pat dry with paper towels. Brush a thin layer of oil on the shoulder, and season the entire roast generously with the set aside seasoning.
Set oven to 300F, and bake for 45 minutes. Take pork out of oven and let rest for 5 minutes. Once rested, shred pork butt using two forks. Use this delicious, juicy pulled pork in a bbq sandwich, tacos or anything else. Enjoy!