Exhaust System FAQ

Please Read Before Purchasing ANY Aftermarket Downpipe

Will your downpipe rub or vibrate?

Absolutely not. Our downpipe design accurately centers the tubing and flex section in-between the firewall and the steering rack while taking motor movement into account. We've proven over the life of this downpipe that our pipe routing is excellent and causes no rubbing or vibrations. Thanks to our precision fixtures we're able to build and ship the same downpipe with confidence day-in/day-out.

Will I get a CEL (check engine light) after installing this downpipe?

Yes. All race series downpipe will cause a CEL. All street series downpipes will eventually cause a CEL.


The Gen3 TSI factory downpipe is equipped with 2 high density catalytic converters. These catalytic converters are packed with precious metals to ensure maximum conversion of harmful gases. 2-3 oxygen sensors are in place to monitor the effectiveness of these catalytic converters. When replaced with a single high-performance catalytic converter, the ECU senses the performance of the catalytic converters has diminished and quickly lights the CEL. Typically, the CEL means you have a bad catalytic converter. The codes generated tell the technician that the catalytic converters have failed. They have NOT.

With any aftermarket downpipe you’re trading one type of performance for another.

The factory ECU expects the catalytic converters to convert nearly all the gases that pass through. The performance of your catalytic converters is constantly monitored. The more gases converted, the better the performance of your catalytic converters. This type of performance refers to the effectiveness of the catalytic converters in removing harmful emissions from the exhaust - not horsepower.

High-performance aftermarket catalytic converters are all about horsepower. Performance is limited by restriction. In order to achieve an increase in performance the catalytic converter must be less dense and less restrictive than the original. This is done by decreasing the cell count and reducing the overall length of the catalyst. With less catalyst in the way, gasses pass through an aftermarket catalytic converter easily, resulting less conversion of the harmful emissions but significantly higher flow. Performance in this case refers to the horsepower gained by decreasing restriction in the exhaust.

What can I do about the CEL?

If the CEL is a problem for you there are options.

Many software tuners offer ECU tunes specifically designed to be used with aftermarket high-flow catalytic converters. These files alter the monitoring system allowing the ECU to be satisfied by a basic 48 state street legal catalytic converter. To learn more about software options, contact your tuner. We cannot advise or guarantee the effectiveness of anyone else's product.

If you're using our street series downpipe with our 48-state legal catalytic converter you may use our Oxygen Sensor Spacer. This spacer restores the balance required by the ECU when using a high-flow cat. 

What are the specs of your catalytic converter?

We use a Magnaflow high-flow catalytic converter. The body is made from 400 series stainless steel. The catalyst is metal with a 200 cell/inch density. It is EPA rated for engines up to 6.2 liters and vehicles up to 6000 pounds. Our catalytic converter is 48 state street legal. (Excluding California & New York)

42 Draft Designs has been using Magnaflow catalytic converters for over 10 years. We have shipped thousands of units with fantastic results. Magnaflow has consistently provided us with high-quality catalytic converters and we're pleased to incorporate their products in our own.

Is there any way to create a high-performance downpipe that won't cause a CEL?

The short answer is No. There are downpipes on the market that claim "No CEL" but don't live up to their claims. There are downpipe out there which come close, but use multiple catalytic converters that are high density and VERY expensive. We don't see the point in creating a high-performance downpipe thatisn't. The only want to assure a downpipe doesn't cause a CEL is to use catalytic converters that match the OEM converters in size, cell count, loading, length, and location. These would cost thousands of dollars and result in only a very slight increase in performance.

What makes the OEM catalytic converters work so well is the loading of precious metals. There is no "cheap" substitute for Platinum, Rhodium, Cerium, Manganese and Nickel. There is no import source and no black market. The only way to replicate the OEM catalytic converters is to use them. Anyone claiming performance gains similar to ours with OEM catalytic converter function is telling you a story.

What is your downpipe made of?

We use 16 gauge and 14 gauge aluminized steel for all exhaust piping. Aluminized steel is a basic carbon steel coated with a aluminum/silicon alloy inside and out. Like any coating, the aluminum alloy protects the steel from the elements and prevents rust. Our aluminized steel holds up to 1600° and will never peel or flake off. The pipe underneath cannot rust until the aluminum the coating is compromised.

The automotive aftermarket community has long claimed aluminized steel to be "cheap" and "junk." In the past 10 years we've proved otherwise. Yes, there is a lot of cheap junk out there. Any auto parts store aluminized steel is going to disintegrate. Any import aluminized steel is most likely garbage. We ONLY use the highest quality North American made aluminized steel purchased directly from the mill to our specifications. Why would we sell garbage?

Fun Fact: Aluminized steel reflects up to 80% of the heat projected onto it. This means our exhaust systems stay cooler over time. Less heat results in more power! (science proves this, but we make no claims)

Our flanges are cut from 1018 cold roll steel. This material machines fairly easily and is consistent. We machine to exacting precision to ensure proper fitment on your vehicle. Precision aside, steel does rust. The flanges will get a light coating of rust on them immediately, but are too thick to “fall apart” within the normal lifespan of this system.

Our v-band flange is CNC machined from 304 stainless steel. The flange is custom made to duplicate the size and female fitment of the OEM v-band flange. Our optional v-band flanges are CNC machined with male/female fitment to our specifications. We use Clampco stainless steel v-band clamps.

Our flex section is 300 series stainless steel with aluminized steel collars. It will darken when heated becoming a dark brown color. This is normal for all stainless steel. The collars on our flex sections are aluminized steel and will share the same characteristics as our piping.

Our catalytic converter is 409 series stainless steel. Grade 409 stainless steel is basically mild steel with enough chromium added to stop rust. It will turn brown in color after heating and may develop slight surface rust. Our catalytic converter is formed using a metal spinning technique, locking the catalyst in place without pinch welds or additional heat shields. It will never leak or rattle.

Our hardware is cad/zinc plated. This plating acts as a protective layer reacting with the corrosive environment before it can reach the steel. We use mechanical locking nuts everywhere to prevent connections from coming loose. We use basic USA standard threaded hardware. In the case of lost hardware you will be able to find what you need at any local hardware store.

If you're worried about corrosion check out our Stainless Steel option!

Corrosion and rust are definitely a factor if you live in a northern state. If you're worried about corrosion, check out our 100% stainless steel option. The function is the same - we've simply replaced everything on the downpipe with 304 stainless steel. Read over the Options Explained tab above for more information.

What size is the stock adaptor?

The stock adaptor is 2.55"/65mm in diameter. Our adaptor is designed to slide into the OEM sleeve clamp.

Can you build me a custom sized adaptor?

Absolutely! Due the undeveloped nature of the Mk7 platform we haven't nailed down a range of standard adaptors. As the aftermarket cat-back market develops we will surely add a few useful adaptors. Until then, we're happy to build any size adaptor you need! Please contact us with your individual requirements. Be prepared to answer some specific questions about your setup in order for us to build an adaptor that will work properly.

What’s that burning smell?

The exhaust should smell like burning oil for about 100 miles. There are oils on the metals leftover from manufacturing. Once burned off, this smell will never return.

Will this downpipe change the sound of my exhaust?

Yes. The increase in pipe size and the change in catalytic converter will alter the exhaust note. There are too many variables to provide a definitive answer, but the exhaust will become louder. Here are some certainties to consider when choosing your downpipe:

  • Race series will be louder than street series.
  • If your aftermarket exhaust lacks significant mufflers your exhaust will be considerably louder with a downpipe upgrade.
  • Thanks to our modular design everything can always be changed. Be on the lookout for our Mk7 cat-back for resonated and non-resonated exhaust options.

Do I need anything else for the installation?

Please read over our installation instructions tab and verify that you have the tools necessary to install this downpipe. Other than the tools listed you will not need anything additional to perform the installation.

How many times can I reuse the gaskets and hardware when switching components?

The gaskets are pretty much one-time use. If you install a test pipe with new gaskets for a track event you can most likely re-use them 2-3 days later when you re-install the catalytic converter. Any extreme heat or significant miles will bond the gaskets to the flanges. This creates a great seal, but they can't be reused. We sell replacement gaskets if needed.

Hardware can be torqued twice. After two torque cycles the bolts will weaken and the locking nuts will lose their effectiveness. We recommend replacing hardware when swapping components. Replacement hardware is available in a kit with a gasket.

Why did you move the second oxygen sensor location?

The second oxygen sensor is located directly after the first catalytic converter. We moved the catalytic converter far away from the turbo to increase exhaust flow and create more power. With the relocation of the catalytic converter the second oxygen sensor naturally had to move. Our new location is well beyond the reach of the wire and electrical connector. To solve this problem we created a plug & play male-female oxygen sensor wire extension that we include with EVERY downpipe. This extension uses OEM connectors and silicone high-temperature sleeving for a perfect fit!