Pulled from CGS Motorsports (Where I bought my 3" High Flow for my Jeep).
Can I install a high flow catalytic converter on my new car/truck?
Legally the vehicle must be 5 years old or have 50,000 miles on the vehicle. The only way to replace the converter before this time is if the stock converter has been removed or been physically damaged leaving it not covered by the factory warranty.
Do I need to have a catalytic converter on my vehicle?
Yes, it is illegal to remove your catalytic converter, in fact you may be fined as much as $5,000 for its removal.