Skunk2 Alpha V2 Header Install – DC2 Integra GSR

In this project we install the Skunk2 Alpha V2 header for the B Series engine on a B Series engine, of course. Specifically in a classic 2001 Acura Integra GSR. 

Build Parts and Tools

Our Integra is OBD2 and needs to stay  compliant. However the original converter uses a smaller collector than the big boy 2.5" collector found on the Skunk2 header.

To ensure we are green and will not have issues with emission requirements in this classics state of residency we are building a custom catalytic converter using a Mangnaflow 2.5″ OBD2 Universal Catalytic Converter and the build process from our Driveway "Any Header" B Series Catalytic Converter article.  Happily ensuring that this high flowing “Off-Road use only”  header will be well suitable for on road use and enjoyment.

An acetylene torch is far more effective and faster than penetrating oil for rusty exhaust bolts.  New gaskets and exhaust bolts help make the install go easier and are good to have if you break a bolt in the process. 


1. Remove front splash shield. 

2. Remove A/C condenser fan.

3. Remove the catalytic converter bolts. This is the hardest part of this whole project. Acetylene torch is the difference between a quick install and a long night struggle.  

The Catalytic converter is held with 2 spring loaded bolts in the front (Collector side) and 3 nuts in the rear. 

4. Disconnect the  secondary O2 sensor in the rear (OBD2) and primary O2 sensor in the front. Remove the catalytic converter from car. 

5. Remove exhaust manifold rear engine block bracket. 

6. Remove 3 lower exhaust manifold bolts and upper exhaust manifold engine block bracket. 

7. Remove upper exhaust manifold shield(3 bolts on front of manifold that will always break) and then the upper exhaust manifold. 

8. Label and remove O2 sensors from original catalytic converter and/or exhaust manifold using 22 mm sensor socket or wrench. 

Catalytic Converter

Having access to a welder we used the Driveway "Any Header" Catalytic Converter process to create a welded custom cat solution utilizing an already existent extension piece from the Integras cat-back exhaust and the Magnaflow 2.5" Unvirsal Catalytic Converter.  

Driveway “Any Header” B Series Catalytic Converter

November 20, 2017

There are two choices for anyone who wants to run a big 2.5″ collector header on a OBD2 Honda. Cheat…

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1. Measure distance between header and cat-back flange. 

2.  Cut end off our extension to length need to connect header to cat-back exhaust. The Magnaflow converter ends are designed to slip over exhaust pipe.  

The Skunk2 provided collector flange fits perfectly on end of converter. 

3. Test fit  Driveway Cat to car, ensuring O2 clearance and position as shown. Adjust for best ground clearance.

Tack in position. Remove to seam weld. 


 1. Using the new Fel-Pro exhaust manifold gasket, assemble header by passing it under car, up through bottom, and into position. 

Tighten header using "center out" tightening method in 3 steps to final torque(23 lbf•ft).

NOTE: Insert and tighten (33 lbf•ft) primary O2 after mounting header.

2. Install A/C condenser fan.

NOTE: Do not forget to connect the A/C compressor wire disconnected during removal

3. Use included Skunk2 Header collector "donut" gasket for the collector side and the Vibrant 3 bolt 2.5" gasket for cat-back connection.

Bolt Driveway "Any Header" cat  to cat-back first then to header collector using spring bolts(20 lbf•ft). Alternate side to side tightening to final torque(20 lbf•ft)

NOTE: Use exhaust spring bolts on collector side. DO NOT use non spring bolts. 

4. Ensure all bolts are tight. Verify both O2 sensors are tight (33 lbf•ft) and plugged in. 

5. Test drive, listen for leaks, and Enjoy.

Keep Wrenching !!