if you like opiates, you should introduce yourself to dxm by using a little bit of dxm with your dilaudid. it basically makes the high into a "super opiate". i think it is my favorite drug combo of all time (morphine and dxm). you start feeling like your body is floating on a warm cloud, and music becomes ultra enhanced - it's like music generates more opiate euphoria. pretty ridiculously cool. but it has a chance of decreasing your breathing, so you should watch out for that.
dxm on its own at high dosages isnt really like opiates too much. it's more of a falling down through a dark warm hole. the body feeling is similar to opiates, for me, but it's more numbing and less buzzing, if that makes sense. it also messes you up more in public than opiates. . at high dosages it becomes really psychedelic, you lose track of what's going on, and you eventually sink deep into a deep mental place where everything is numb, and you get visuals and feelings of merging with a white light.
as far as zicam. it's the best way to do dxm. . i consider it the luxury way of consuming dxm, because it's so motherfucking expensive ($8 or so for a single spray cylinder where im from). it hits *fast* and *hard*, especially if you drink it. i like it because it offers a way of controlling how high you get very easily. let's say i'm at 1st plateau for a few hours and then i want to go to 3rd or 4th. i just spray 50 more sprays or so and 15 minutes later im getting a fast elevator ride down to the next level of abyss. then again. for people who are into the extreme rushes, just pounding a couple of the canisters as liquid form is probably one of the craziest rushes that's out there, legal or illegal. this way, i usually reach the peak of the high in about 45-60 minutes (less than half the time from the gelcaps, my 2nd preferred method)