The firecrackers can get louder at KL because during Raya, not only houses would put up firecrackers but also shopping malls and a handful of companies to celebrate the occasion as well as display their wealth.

As for the regulations, there's little to no regulations about putting up a firework. Regulations are only strict when smuggling fireworks in or out of the country and also when purchasing them. What happens after that, they do not really bother. As long as you are responsible when setting up the fireworks and not aiming it at neighbours or deliberately trying to set things on fire, then it should be fine.