Hey, I wanted to give my two sense about this since I have a degree in neuroscience and work on the daily with drugs. I've also personally dosed opiates with baclofen. I weigh about 160lbs and with 10mg of Vicodin (Sometimes more spread out over time after) synergized with around 40mg of baclofen about an hour after taking the opiate and it was like I was on a fluffy euphoric cloud for quite awhile (Maybe 4-6 hours depending on variables). However, I wouldn't recommend you start at those amounts unless comfortable with how your body will respond. Using more than 40mg of bac really isn't needed and could start to get far too depressive after that point imo. I'd try lower doses around 10mg of bac about an hour after taking the opiate. Also, and this should go without saying, but please avoid other depressants like alcohol when using these. These drugs are not toys to fling around with other drugs willy nilly and should be given proper respect, especially without experience with them. Stay safe.