diesel regulations

my little brother is about to get a 1991 ford f-250 diesel. is he required by law to have a cat and muffler??

wow. big font and in all caps was that necessary. I would guess so, but a lot depends on what state, county, township you live in... I would do a google search

No need to shout.
If it came out with it OEM it is required to operate on a federal hwy..

you must goggle the year and EPA. every year thay change the requirements. or at least get a Chilton's repair Manuel. it should have a thing two on the exost system. yes the EPA changes what system the trucks must have on them year by year. i have seen the exact same trucks lose fuel mileage just because there was one little change in the set up by the EPA.