So i just bought this 2004.5 GLI, looks sick and all. But here is my problem. The car has 146k miles on it. it has a stage 2 APR chip in it and also the turbo is leaking oil, causing the car to lose ALL the oil (apparently). When i bought it, and drove it home, checked the oil and it had none, zero oil, so i went to Walmart and bought some 5-w30 full synthetic oil and filled it up, now, the car is currently at the shop because i dont know how to replace the turbo, so im going from a ko4 to a ko3, but the current tune in the car is for the ko4, if i drive it without a new tune, will it blow up on me? the car is running 26 psi. Also, when i put it in first and start going, the car smokes out of the exhaust, im assuming that this is oil burning from the turbo leak. I need you guy's advice on this, i dont wanna ruin this car!! so any tips and all, what should i do!??

PS. this is a 1.8t engine.
Thanks!