One of the first and probably the cheapest modifications you can make to your car is to fit a bigger (noisier) exhaust.
Exhaust manufacturers will cite increased power as a reason to change your exhaust system. Be mindful of the fact that the manufacturer has already spent millions of dollars designing your vehicle to perform at its best and simply bolting on a muffler or a bigger diameter exhaust pipe may not give you a noticeable increase in performance.
Before you start to modify your exhaust system it would be a good idea to check with the supplier that the exhaust meets all necessary noise emission and pollutant emission standards. All cars when first registered in Australia must comply with Australian Design Rule 28 or 28A with regard to vehicle noise. This rule sets the vehicle exhaust noise standard.
The standard for passenger cars is 81 decibels (dB(A)) and 82 dB(A) for off-road passenger vehicles.