Though most people in the country opt for root horns and other such aftermarket loud horns to get people to move out of their way, these are illegal. According to the CMVR, the maximum output from the horn can be 82 dB. Anything more is illegal. The main reason behind that is that it is very irritating to the human ear.
Loud exhausts are something that all enthusiasts enjoy. Sadly, they too are illegal. A RTO in Maharashtra recently seized a Bullet for being too loud (Read here).
The same is the case for cars as well.According to the law, a passenger car shouldn’t emit more than 80-83 dB of noise while running.So if you are planning to get your exhaust changed make sure it is below the prescribed limit or is used on private roads.
Weight change of more than 2%
According to the law, you are allowed to make changes in your car as long as the weight doesn’t change by more than 2% of the original unladen weight given to the RTO. Anything above that is illegal, unless approved by the RTO.
Remaps/tuning boxes, ECU swaps all are illegal. Why? The cars undergo a rigorous test for emissions to make sure all norms are being met. Changing the power and torque curve could change emissions the car was certified for and hence makes the car illegal to drive on public roads. Popular brands selling tuning boxes include Pete’s, Race Dynamics, Race Chip and Spider Tuning. Tune-o-Tronics, Pete’s, Wolf Moto and Code-6 are popular re-mappers.
Since the car is tested with the engine and each car has the engine and chassis number engraved on the RC, changing the engine and swapping it with a new one makes the RC illegal. In case you do want to change the engine, approval is required from the RTO and it can only be changed to something that has been homologated with that car. Any other engine swap is illegal.
*Some modifications can be made legal, but the process is a long, expensive and cumbersome one. First, you will have to send the modification plans to the manufacturer, who will study the design change and then approve/disapprove it. If that it is approved, you can go ahead with the modifications. Once modified, you will have to get the vehicle tested by the testing agencies (ARAI/ICAT/etc) at your own cost. Once the vehicle has been approved, you can go the the RTO to get that legally endorsed on your RC. The problem with this is that it is a very expensive and time consuming process. So for an individual doing it, it is not recommended.