Find out what they're testing for. If they're doing the standard drug abuse tests that most employers to, your test levels wouldn't even be looked at so you wouldn't have anything to worry about. But if they are testing for steroid use too and you're taking the Havoc it's going to show up. You can always play dumb and tell them "I bought it at a GNC, I've taken test boosters before, I wasn't aware this wasn't allowed."