T3/4 Turbo is very good, rods will need uprating unless you tune in accordance to what your stock internal setup will hold.
With turbo systems you will always have two wastegates, one on turbo or close, and another in the system before the throttle.
On the 1.8T you have a DV which recirculates, the aternative is an atmospheric valve. As then you close the TB you will have pressure in the system which you either release atmospherically or recirculate. If this was not in place the pressure would have to change direction, this causes the turbo to stall.
Same thing with turbo's you will have an actuator like on the k03 that opens up, alternatively the other option is a screamer valve which releases atmospherically, this is on turbo's with no actuator like the T3/4.
Other option depending on what power you are aiming could be a k04-001, k04-023, garett gt28xx etc...