To paraphrase the actual wording of the VAT (Vehicle and Traffic code):
You are not allowed any exhaust modification that makes the car louder than stock
Here is the actual wording of Title 3, Article 9, Section 31 of the VAT; the one that deals with the muffler system:
- Mufflers and exhaust systems. Prevention of noise. Every motor
vehicle, operated or driven upon the highways of the state, shall at all
times be equipped with an adequate muffler and exhaust system in
constant operation and properly maintained to prevent any excessive or
unusual noise and no such muffler or exhaust system shall be equipped
with a cut-out, bypass, or similar device. No person shall modify the
muffler or exhaust system of a motor vehicle in a manner which will
amplify or increase the noise emitted by the motor or exhaust system of
such vehicle above that emitted by the muffler or exhaust system
originally installed on the vehicle and such original muffler and
exhaust system shall comply with all the requirements of this section.
So basically, cop’s knowledge > your knowledge.
If you’re interested, you can search the entire thing here:
http://public.leginfo.state.ny.us
Just click on “Laws of NY” and read.