I think the term "legal", regarding Roush or other exhuasts, or cai's for that matter, means in regard to emissions testing.

Localities can make whatever subjective "decibel level" laws they want.

Da Bears... Da Bulls... Now THOSE are offensive sounds!!

 

A cat back exhaust has nothing to do with emission standards.

 

Well wait then.. please to explain.. lol...

What does the "legal" vs. "off-road" terminoligy refer to?

I can understand how a given manufacturer can certify that they comply with emissions standards in all states, understanding that really it's only Ca. that they have to satisfy.

But decibel levels are a very different thing. Any city, state or burg can set any arbitrary noise level they want. There's no way any aftermarket exhuast manufacturer / seller could claim to be "legal" regarding the sound they emit. What's fine in one town might be heinous in the town next door.

Here in Austin there are "laws" about the decibel level from cars regarding stereo systems. Not the they're enforced. Thump thump thump, etc... much more annoying than any exhuast sounds..

 

The legal kit is street legal in terms of loudness and the offroad kit is louder in terms of sound. The difference between the two kit wise is the muffler.

 

I agree with TexEdition.

Legal with regards to emissions is not the same as legal with regards to noise levels.

The Illinois vehicle code clearly states: "No person shall modify the exhaust system of a motor vehicle in a manner which will amplify or increase the noise of such vehicle above that emitted by the muffler originally installed on the vehicle..."

If the Roush exhaust is louder than that of the muffler originally installed on the vehicle then it is illegal. Why is that so difficult to understand?

 

You said it all with two letters, if. What's to understand here? If isn't a certainty.

Roush modifies the Roush f150's, I'm all but positive they modify those trucks with their equipment, or should I say if.

 

Yes, IF.

So how can you say with certainty "A Roush kit is completely legal since they're sold on Roush f150's" and "The Roush legal kit is just that, legal, no matter what f150 it's for." IF you don't know the decibel level of the exhaust originally installed on his 2004 F-150 and IF you don't know what the decibel level will be IF he installs the Roush kit?

 

Exactly! I'm sticking with my story. You stick with yours. We're both happy. I haven't even been to Illinois. Maybe he should do his research into seeing if (there's that word, again) the Roush street legal kit is actually legal in the state if Illinois or not. I bet those in charge can't even give him the same answer twice.

 

I don't understand how a noise law can be applied differently for different vehicles. Obvilusly, what is stock for one is not stock for another. A GT Mustang is going to be louder than a Civic. I bet a lawyer could tear that one up in court.

 

Once again, IF it is louder than his original exhaust which the vehicle came with it is illegal, IF it is not louder than his original exhaust which the vehicle came with it is legal.

A blanket statement that the Roush kit is either totally legal or totally illegal in the state of Illinois (in regards to noise) won't work, it is dependent on the specific vehicle.

 

It's all in the interpretaion of the law, and we all know people interpret things differently in any given situation. Just because it's weitten X way doesn't mean it is going to be interpreted X way.

 

OK, so then using that logic he can put whatever exhaust he wants on the vehicle and tell that to the police and/or judge the next time he gets pulled over.

 

You actually think Policemen and/or judges can interpret this vague law?

 

I don't think it's vague nor do I think the interpretation is that difficult. Although for some people who don't comprehend this may be what lawyers are for. I do think proving the sound levels are greater than that of the original muffler is a different issue. But the law is clear.


I can see someone who thinks the law is vague asking "those in charge" and getting the following answers:

Question #1: "Is a Roush exhaust kit legal (in regards to noise) in the State of Illinois?"

Answer #1: "Sir, if it amplifies or increases the noise of your vehicle above that emitted by the muffler originally installed on the vehicle, it is illegal. If it doesn't amplify or increase the noise of your vehicle above that emitted by the muffler originally installed on the vehicle, it is legal."

Question #2: "How about a JBA exhaust kit? Are those legal (in regards to noise) in the State of Illinois?"

Answer#2 : "Sir, if it amplifies or increases the noise of your vehicle above that emitted by the muffler originally installed on the vehicle, it is illegal. If it doesn't amplify or increase the noise of your vehicle above that emitted by the muffler originally installed on the vehicle, it is legal."

Question #3: "Ok, what about a Borla exhaust kit? Is that legal (in regards to noise) in the State of Illinois?"

Answer#3 : "Sir, if it amplifies or increases the noise of your vehicle above that emitted by the muffler originally installed on the vehicle, it is illegal. If it doesn't amplify or increase the noise of your vehicle above that emitted by the muffler originally installed on the vehicle, it is legal."

Question #4: "Um, oh. Well how about that Roush exhaust kit I mentioned? Are those the ones that are legal no matter what F-150 it's for (in regards to noise) in the State of Illinois?"

Answer #4: "Sir, if it amplifies or increases the noise of your vehicle above that emitted by the muffler originally installed on the vehicle, it is illegal. If it doesn't amplify or increase the noise of your vehicle above that emitted by the muffler originally installed on the vehicle, it is legal."

 

OK, so, like I have been saying, the Roush street legal (Yes, street legal, the key words here) kit will be just fine.