MACH I Member
Joined: Jul 2008
Location: Long way from home
Check your local laws instead of listening to the lawyers on this forum. There are a ton of things that are illegal to do to a car but most of the time either the cops don't know or care and people never get hit with the fines. There is no rule of thumb, only rule of law.
Federal law makes it illegal to modify or remove any emissions control device on a car. The fines are high, but enforcement is low.
State law adds another layer to the motor vehicle laws. Most likely it is not against the law to do what you want, but if you pay close attention to most descriptions for auto parts on performance websites most clearly state off-road use only so that in the event of a ticket they are not responsible, you are.
1988 Mustang LX coupe will miss you greatly
2004 Mazda 6s 5 door Sport w/5spd/3.0/RX8wheels/Kon/Eibach/and then some