As to adding codeine cough syrup, even if you have the right enzymes, redosing codeine doesn't work too well. Without tolerance, I'd expect most people to get a mild, fuzzy warmth from 60mgs of codeine, but you'd probably get higher from a joint or a few beers. T3's are really best for pain management and a Godsend when you have to function on bad hangovers (I find that to be true even with a substantial opiate tolerance), but if you want a high, then codeine'll only get you there if you have it in pure form or risk a CWE, which is a bad habit to get into (I started out with codeine, and soon hit the harder stuff). If you try again on an empty stomach, you might have better luck - especially if you take a tagamet and/or fresh, pulpy white grapefruit juice 45 mins to an hour before dosing. You might have a high natural tolerance, and you can't safely take more than two T3's at a time, owing to the APAP, while CWEing always runs the risk of imperfect filtration and resulting liver damage. I'd leave the cough syrup (it probably has other actives in it, too), and if you're determined to experiment with opiates, wait until you come into contact with something a little stronger (Vicodin/Norcos or even Percocet, perhaps - but starting down that road can lead to a lifetime's regret. I've lost a couple of years to pharms, opiates and benzos - and it all began with codeine and kratom).
I disagree, from a recreational viewpoint, that a T3 = a 5mg Vic. Technically, sure they're equipotent, but hydrocodone is much more euphoric, to me, than codeine - even with a moderate tolerance, my first 5mg vic resulted in a much buzzier, upbeat high than I'd get at the time from a 30/500 codeine.APAP pill. And high-dose, extracted hydro is one of my favourite opiates (tried everything but Dilaudid and oxymorphone, pretty much). I've spent a lot of time in the US, but am currently living in a shitty island off the coast of Europe, and the two creature comforts I miss most from the States are Hydro CWE's, preferably from Lortabs, and cold draught Root Beer: the combination would make me a very happy man right now, especially with a Wendy's cheeseburger or three and some peanut butter M&Ms. No, not Reese's Pieces: peanut butter M&M's. They'll getcha higher than codeine, though they're more addictive. I swear, I may be a benzo and opiate addict, but it's all a result of abrupt cessation of root beer, Wendy's & peanut butter M&Ms. That shit was doper than what's sold as dope here, even without the hydro.