Section 4. Mandatory Installation of Speed Limiter.— No covered vehicle, following the effectivity of this Act, shall be allowed to run in any road, street or highway in the Philippines without a standard speed limiter in accordance with the standards and specifications approved by the DOTC; Provided, That in case of vehicles which are already registered with any appropriate agency, this requirement shall be complied with not later than eighteen (18) months from the effectivity of this Act.