So ive tried dxm a couple times with little effect. I did between 200-400mg around 4 times. couple of times with no effects except being a little slow. Last time (390mg) just made everything slow and i had no balance. Im looking to do it one more and hopefully have an experience and some enjoyable effects. Since 400mg did barely anything, i was thinking of doing 500-600mg while drinking grapefruit juice just in case i dont get any effects. Is this a good idea or should i do higher dosage? Lower? By the way i am 5'8 160 lbs 19 years old.