Swapping a 1.8 (BP) into an early 1.6 (B6) NA is a classic, sensible upgrade, but be honest about the payoff: the 1.8 makes only modestly more power. The bigger reasons to do it are torque, the stronger later drivetrain, and a fresh engine.
The 1.6 is a gem, light and eager, but it's down on displacement. A BP swap is well-trodden ground with lots of community knowledge
…