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JHM Headers (V2) - C5 Allroad (4.2L)

Catalytic Convertors

PLEASE READ! These headers are designed for the B6-B7 S4 chassis and will work on the C5-allroad 4.2L with some modifications. These modifications consist of; Clearancing the driver side transmission bracket, modification of the oxygen sensor J-bungs, and adapting the header downpipes to the C5 catback (we offer and recommend the Magnaflow System).

NOTE: These headers fit both the factory Automatic Transmission with the modifications shown or a 0A3 conversion using the JHM mounts.

Here is a PDF that shows the minor modifications required to make this work on the C5-allroad 4.2L: Click HERE


Introducing our new and improved, JHMotorsports Version 2 Mid-Length Headers for the B6-B7 S4 with the 4.2L 40v V8!!!






Due to current demand on JHM Headers, there is currently a 4-6 week lead time.


Our Version 2, Mid-length Headers are an improvement on one of our most popular and successful modifications for the B6-B7 S4 with the 4.2L 40v V8. These re-designed headers are a well rounded performance upgrade that will net gains to all range of B6-B7 S4s with very little compromise. This includes cars with a stock motor and bolt-on modifications to fully built motors with superchargers running high boost.


Click to enlarge picture
Audi S4 Headers - Mid-Length Stainless


Click to enlarge picture
Audi S4 Headers - Mid-Length Stainless


Click to enlarge picture
Audi S4 Headers - Mid-Length Stainless


Click to enlarge picture
Audi S4 Headers - Mid-Length Stainless


Click to enlarge picture
Audi S4 Headers - Mid-Length Stainless


Click to enlarge picture
Audi S4 Headers - Mid-Length Stainless




When we first released our headers in 2008, our design was meant to maximize torque. Since then, we've pushed the B6-B7 S4 platform a lot further and we started to find that we'd need something bigger that didn't sacrifice torque. In 2012, we started to look at revisiting the design to make improvements that would keep the product growing with the market. We started testing our redesigned headers in 2013 as we started putting built motors in the B6-B7 S4.


Although they were an excellent product, our original long-tube headers are no longer available.




Our new headers are a mid-length style header with a larger primary runner size. Generally, longtube headers make more torque and short tube headers make more horsepower. Mid-length headers bring you the benefits of both. The larger primary sizes opens up the motor more leaving room for growth with supercharger kits, built motors, and more boost. Back in 2008 when we first came out with the headers, long tubes with smaller primaries were the way to go - we didn't have our upgraded intake manifold yet, the exhaust systems for the platform were still small, and our tuning for the B6-B7 S4 4.2L V8 was still evolving. Once we came out with our upgraded intake manifold, we found that the OEM dual-runner design was able to give the motor a lot of torque. Then, we started to build the motors to handle more power and more boost and once we did this, we found that our headers from 2008 were corking the motor.




When compared to our original header design, these new headers will give you more power on the top end without sacrificing power down low. They'll allow you to take advantage of more of our modifications like the JHM Intake Manifold or the JHM Supercharger Kit or even our built motor. As of December 27th, 2014, we've gone 11.1 at 128 mph with our in-house B6-S4 which features these headers, a fully built motor, and our Vortech Supercharger kit. More results are coming soon!


They are also more modular and easier to install. We've made them specific to either manual or automatic transmission cars and you can also use your stock oxygen sensors with these headers instead of having to buy longer sensors or re-wire and lengthen your oxygen sensors.




Our JHM Version 2 Headers are a COMPLETE replacement for the restrictive OEM exhaust manifolds and OEM downpipes. Our headers will connect directly to a JHM-Fast Intentions true 2.5 inch cat-back or any other cat-back with a 2.5 inch connection to the downpipes.


-2004-2005 C5-allroad 4.2L


- 1x Stainless steel, driver side header assembly with v-banded flange 
- 1x Stainless steel, passenger side header assembly with v-banded flange 
- 1x Stainless steel, driver side downpipe with v-band connection 
- 1x Stainless steel, passenger side downpipe with v-band connection 
- 2x V-band clamps for header to mid-pipe connection


- 2x OEM exhaust manifold gaskets 
- 3x OEM exhaust manifold studs (to replace the 3 bolts removed) 
- 3x OEM Exhaust manifold nuts (to replace the 3 bolts removed) 

- 2.5" Stainless Steel Exhaust Clamps (Pair) for mid-pipe to cat-back connection: Search for 10162-pair and add to your cart for a new pair of high-quality, 2.5" exhaust clamps for the connection between our headers and your 2.5 inch cat-back 
- Heat Shielding for the Transmission selector switch if you do not have any.  Search for 010392 on our site for DEI Reflacta Gold which we use and add to cart.


- The engine MUST be lowered substantially or removed from the vehicle to install these headers.
- Our headers have primary oxygen (O2) sensor bungs that are close to the stock location but end up pointing the sensors in a different direction. When routing the O2 sensors it is VERY important you secure the wires so they don't rub on anything. Specifically, make sure that the sensors are clear of the shift linkage on the driver side of the transmission and that they aren't close to the exhaust pipes so they don't burn through. Zip ties work really well for securing the sensor wires.
- When removing your O2 sensors from your stock manifolds and downpipes, it is very helpful to label the sensors to note which sensor is for the primary versus secondary location and the driver versus passenger side. The O2 sensors must be installed into the same location they were removed from.
- Once you install our additional studs you will have studs and nuts for ALL of the mounting holes. Torque all nuts on the cylinder head to header flange mounting studs to 25Nm or 19ftlb.
- It can be difficult to get to the lower nuts on the headers so you will need to get to those first and use tools like crow's feet and Gearwrench box end wrenches. Once the headers are fully secured and tightened, you can re-install the motor mounts.
- The alternator may have to be removed to install the headers in order to gain access to certain nuts. Some cars may require the alternator coolant pipe bent slightly for additional clearance.
- It is HIGHLY recommended to wrap the headers in the area where the stock manifolds were located to keep heat from the factory wiring, motor mounts, alternator, and coolant pipes. You should only have to go about 1 foot at most past the end of the motor since the factory downpipes were not shielded and our headers travel along the same path.


Like many of the performance products we sell on our website, these headers are for OFF-ROAD USE ONLY!!! Ordering these headers with our high-flow catalytic converters will NOT change this. With that being said, our high-flow catalytic converters do well to reduce hydrocarbons and carbon monoxide (HCs and CO). However, they are limited in their ability to reduce Nitrous Oxide (NOx). Customers in the state of California with our high-flow catalysts have told us that they have passed the tailpipe or "sniffer" smog test with our cats installed. Remember that aftermarket catalytic converters are not legal for public road use in the state of California. Though they may pass an emissions test out of the tailpipe, they will still fail a visual test. In the state of California ONLY stock catalytic converters or catalysts with a CARB EO number are technically "smog legal." Our high-flow catalysts do not have a CARB EO number. Please refer to your local laws and regulations for more information.

Tags: 2001 , 2002 , 2003 , 2004 , 2005 , Allroad , Audi