JHM Exhaust Headers - B6 / B7 S4 - 4.2 V8 - Version 2
Please note that there is a currently a 4-6 week lead time for construction of these headers.
JHM's Version 2, Mid-length Headers are an improvement on one of their 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.
WHY A VERSION TWO?
When JHM first released their headers in 2008, their design was meant to maximize torque. Since then, JHM has pushed the B6-B7 S4 platform a lot further and they started to find that they would need something bigger that didn't sacrifice torque. In 2012, JHM started to look at revisiting the design to make improvements that would keep the product growing with the market. JHM started testing their redesigned headers in 2013 as they started putting built motors in the B6-B7 S4.
Although they were an excellent product, the JHM original long-tube headers are no longer available.
ABOUT THE REDESIGN
JHM's 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 JHM first came out with the headers, long tubes with smaller primaries were the way to go - JHM didn't have the upgraded intake manifold yet, the exhaust systems for the platform were still small, and their tuning for the B6-B7 S4 4.2L V8 was still evolving. Once JHM came out with their upgraded intake manifold, they found that the OEM dual-runner design was able to give the motor a lot of torque. Then, JHM started to build the motors to handle more power and more boost and once they did this, JHM found that their headers from 2008 were corking the motor.
When compared to the 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 other modifications like the JHM Intake Manifold or the JHM Supercharger Kit or even a JHM built motor. As of December 27th, 2014, JHM has gone 11.1 at 128 mph with JHM's in-house B6-S4 which features these headers, a fully built motor, and the JHM Vortech Supercharger kit. More results are coming soon!
The new headers are also more modular and easier to install. JHM has 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.
JHM HEADERS AND CAT-BACK VERSUS OEM EXHAUST COMPONENTS
The JHM Version 2 Headers are a COMPLETE replacement for the restrictive OEM exhaust manifolds and OEM downpipes. JHM 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.
- 2003 to 2005 B6-S4 Sedan, Avant, or Cabriolet with Manual or Automatic Transmission
- 2005.5 to 2009 B7-S4 Sedan, Avant, or Cabriolet with Manual or Automatic Transmission
- 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
PARTS REQUIRED - JHM INSTALL KIT WITH THE FOLLOWING: Search for JHM-B6S-LTH-INSTALL-KIT
- 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 the JHM headers and your 2.5 inch cat-back.
OPTIONS: Select your choices from the drop down boxes above
- Downpipe Configuration: JHM offers downpipes for JHM Version 2 headers with or without high-flow catalytic converters. The JHM catalytic converters are a high-quality, racing cat with a spiral metallic substrate. JHM also gives you the option to order both "straight pipe" mid-pipes AND "cat-pipe" downpipes (a total of two sets of downpipes).
- Transmission Type: The JHM Version 2 headers are now transmission specific for better installation. Select "Manual" or "Automatic".
- The engine MUST be lowered substantially or removed from the vehicle to install these headers.
- JHM 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 do not 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 do not 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 the 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 the JHM headers travel along the same path.
**THESE HEADERS ARE FOR OFF-ROAD USE ONLY**
Please note that these headers are for OFF-ROAD USE ONLY!!! Ordering these headers with high-flow catalytic converters will NOT change this. With that being said, the 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 the JHM high-flow catalysts have told JHM that they have passed the tailpipe or "sniffer" smog test with their 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." JHM's high-flow catalysts do not have a CARB EO number. Please refer to your local laws and regulations for more information.