Mr. Jim Wilder

Undercar Digest

MD Publications, Inc.

P.O. Box 2210

Springfield, MO 65801-2210

Dear Mr. Wilder:

Thank you for the questions you faxed to us on May 14, 1991 concerning exhaust repairs and dual exhaust. Below we have repeated the questions and provided a response for your readers.

Question 1. If a 1975 or newer V-8 equipped vehicle has OE dual converters coming off the exhaust manifolds and then forms into a single exhaust pipe, can I dual the system out directly behind the converters?

Answer: No. Federal law prohibits any person from removing or rendering inoperative any emission control device or element of design installed on or in any motor vehicle or motor vehicle engine. The exhaust system configuration, including the location of the converters, and the exhaust pipe diameter and length, are items specified by the manufacturer during certification because engines and some of the associated emission systems are generally affected by the exhaust backpressure, which subsequently affects vehicle emissions. Thus, the backpressure and the exhaust system configuration are elements of design of the emission control system as certified by the vehicle manufacturers. Therefore, any change to that system could be considered a violation of federal law. Additionally, such an installation may also void the emission warranties afforded vehicle owners under section 207(a) and (b) of the Act.

While we would not recommend, encourage or endorse any exhaust modification that makes the vehicle different than the original system, at the present time we are not pursuing enforcement actions if a muffler or repair shop merely puts on "fake" dual exhaust systems after (not at) the last converter and after the exhaust system has been wyed together to a single exhaust pipe.

Question 2. Can I dual it out from behind the single exhaust pipe?

Answer: As the second paragraph of the response to question 1 indicates, we would not recommend, encourage or endorse any such modification because it may void the warranties and adversely affect the performance, fuel economy and even exhaust emissions in some cases. However, at the present time we are not pursuing cases if someone duals out from behind the single exhaust pipe with "fake" duals after the last converter and after the exhaust system comes together to a single exhaust pipe.

This should not be construed to mean that you can use one of the direct fit converters marketed by some manufacturers which have dual outlets and either dual or single inlets to start the duals at the converter. We consider this type of modification to be a violation that we will enforce.

Question 3. Can I install glasspacks or small turbo mufflers instead of direct-fit or cataloged replacement universal mufflers?

Answer: Again, as explained in the response to question 1, exhaust backpressure is an element of design of the emission system and any change could be considered a violation because of the possible effects on emissions. However, EPA is currently not pursuing enforcement actions on these types of potential violations at the present time. Any such changes should be approached cautiously because of the potential to adversely affect emissions, performance, and warranty coverage.

Question 4. Can I drastically change the pipe configuration on a vehicle, as long as it is behind the OE converter configuration (side pipes or stacks on pickups, for example)?

Answer: The same answer applies here as the previous three questions. EPA is currently not pursuing enforcement actions on potential violations that are down stream of the last converter in the system and downstream from where the exhaust system comes together as a single system. The same concerns about the potential problems with warranty coverage, emissions, and performance mentioned above apply here as well.

Question 5. Prior to passage of the new Clean Air Act Amendments, vehicle owners could not be prosecuted by the federal government for tampering with their own vehicles. Can I work on a vehicle that was tampered with by a Do-It-Yourselfer, prior to November 15, 1990?

Answer: Yes, you can work on a vehicle that was previously tampered with. However, if you are replacing a part that is not the proper part for that vehicle and emission system, then you are required to put the proper parts back on the vehicle if you have to remove them for any reason. The installation of improper parts or components which defeat, by-pass or render inoperative any emission control part or element of design originally installed or designed into the system by the manufacturer, is illegal. In other words, if you perform any work on any part of the vehicle which has been previously tampered with, you must perform the correct repair or not do it at all in order not to be liable for tampering. This is true regardless of the age or mileage on the vehicle and applies to any motor vehicle which was designed to meet federal emission standards. For passenger cars and light-duty trucks, this means all 1968 or newer model years.

Also, if you perform any work on a vehicle that has been tampered with, you should document the condition of the vehicle when it came into the shop and precisely what work was performed to protect yourself from being accused of doing the improper work. You should do this by at least noting it on the invoice and possibly have the customer sign an acknowledgement. Photographs or drawings stapled to the invoice are also helpful.

In addition, if you or any person assists in the completion of any tampering (such as installing dual exhaust where the customer has installed headers even if converters are installed on both sides), that person has participated in the act of tampering begun by someone else and is also liable for the tampering violation. If someone has installed headers on a vehicle and wants you to complete the work of installing dual exhaust, you should recommend that it be put back in the original configuration. If the customer refuses to do that, then the only thing you can do is restore the system to a single system immediately behind the headers and put any required converters in the proper locations.

As mentioned in our recently released Exhaust Repair Guidelines, one exception to this is if the customer comes in with an already complete dual exhaust system that is rotted out and is willing to put on converters on each side. The only other exception is if the vehicle is a heavy-duty truck which did not have any converters when it came from the factory. Since these vehicle engines only had maximum backpressure specifications when they came from the factory and no minimum backpressure specifications, it would not be illegal to install a dual exhaust system on such a vehicle.

Question 6. Who should I call if a vehicle that has been tampered with comes into my shop for exhaust system repairs and the vehicle owner refuses to allow me to make the system legal? I don't want to be prosecuted for something I'm not responsible for?

Answer: As long as you don't tamper with the system, help someone finish or complete the tampering, or install an incorrect part or system on a vehicle, you would not be liable for any violations. A prudent repair shop may want to refuse to do any work unless the vehicle owner authorizes complete restoration to the original certified configuration.

We would recommend that any repairs performed on a vehicle which has been tampered with be approached with caution and that appropriate measures be taken to precisely document the condition of the vehicle when it entered and left the shop. If you don't even work on the vehicle you may still want to fill out an invoice and advise the customer of the needed repairs. If you refuse to perform certain work which is illegal and you believe the customer is going elsewhere and getting it done, we recommend that you write down the date, customer's name (and address), make, model, year, license number, the condition of the vehicle when it left your shop, and where you believe he (or she) is getting the work done along with any information which leads you to that conclusion. Any information concerning tampering can be sent to our enforcement staff in either Washington, D.C. or Denver, Colorado (western half of the country) at the following addresses:

U.S. EPA U.S. EPA

Eastern Field Office Western Field Office

FOSD (EN-397F) 12345 W. Alameda Parkway

401 M Street, S.W. Suite 300

Washington, D.C. 20460 Denver, CO 80228

(202) 382-2938 (303) 969-6476

The more information you supply us with the more likely it is that we can do something about it. If necessary, you can remain anonymous. Some people think that this is "tattling" but we believe that you should recognize it as helping to keep the air clean for all of us. We also believe that enforcement is necessary to level the "playing field" and make all the players play by the same rules so that shops doing legitimate business will not be at a competitive disadvantage. We realize that those are precisely the kind of pressures that encourage illegal activity.

We appreciate the opportunity to respond to these questions and hope it helps clarify these matters for your readers. If we can be of further assistance in clarifying these matters, please let us know.

Sincerely,

Mary T. Smith

Director

Field Operations and Support Division

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