Rangers, 1995 and up had an O2 sensor added after the Catalytic converter(s) as part of the emissions system, it tests if Cat converter is working by comparing the upstream O2 oxygen levels to the downstream(after cat) oxygen levels.
So anything after the downstream O2 sensor wouldn't be part of the emissions system, but.............
Non-stock exhaust can "flagged" and you may need to pay extra to have an inspection to certify and changes meet requirements.
Louder is lower frequency sound waves, just add larger diameter pipes, after Cat converter(s), and that will make exhaust louder.
Last edited by RonD; 06-24-2016 at 10:46 AM.