Taking MAO inhibitor along with DMT makes the trip 4-6 hours long. This combination is actually what's in ayahuasca. But don't take MAOI without any preparations as it turns off the blood-brain barrier, allowing toxins to enter the brain, which might kill you. Having a carefully assembled diet for at least 2 weeks is required to clean up the body beforehand.
https://www.verywellmind.com/foods-to-avoid-when-taking-maoi...