It’s all staute that governs modifying cars, just to different extents and by different means. Different strokes for different nations. Literal strokes in this case.

Singapore has a population density around 7800 people per square kilometer. With that many people, many of whom ride motorcycles because its so crowded, regulating their noise and emissions output is in everyone’s interest. Singapore also does not fuck around with punishments. They have mandatory canings for some lower crimes and they execute hundreds of people a year for drug offenses.

The US does similar things. You aren’t allowed to modify the ECUs on cars to push them outside EPA standards. A truck mechanic got tagged for installing devices that let people roll coal and ended up with huge fines.

You do in Singapore.

Good news: they tend to be much larger than tigers so there’s even more to hug!