Skunk2 Alpha Header (06-11 Civic Si)

Apply penetrating oil to the three nuts that mount the exhaust system to the stock catalytic convert pipe.

Remove the three nuts.

Remove the four 10mm bolts that hold the heat shield to the catalytic converter.

Removing the heat shield will ease in the removal of the o2 sensor.

Remove the lower portion of the heat shield, the upper will remain until the o2 sensor has been removed.

Prepare the o2 sensor for removal with penetrating oil.

Using an crescent wrench or an o2 sensor socket, remove the o2 sensor from the catalytic converter.

Optional: Tuck the o2 sensor up on the heat shield so that it does not get in the way of the removal of the factory exhaust manifold and catalytic converter.

Unplug the primary o2 sensor from the plug that is attached to the firewall by pressing on the release clip.

Remove the two 12mm spring bolts that attach the catalytic converter pipe to the exhaust manifold.

Remove the exhaust hanger from the catalytic converter pipe.

Remove the catalytic converter pipe.

Remove the two 14mm bolts that hold the sub-frame harness to the steering rack.

Lift the bracket away from the steering rack and push towards the engine and tuck it out of the way. This will aid in the removal of the factory exhaust manifold.

Remove the two 14mm bolts that attach the exhaust manifold to the engine block and remove the support bracket.

Remove the three 12mm bolts that attach the half shaft cover from the engine block.

Installation of the cover after the install is complete is not required.

Remove the heat shield from the exhaust manifold by removing three 12mm bolts.

There is one at the bottom and two on each side at the top.

Remove the heat shield. Some force may be required.

Remove the three 14mm bolts and two 14mm nuts from the factory exhaust manifold mounting points.

The exhaust manifold will rest on the upper studs once the all of the bolts/ nuts have been removed.

Remove the two 12mm bolts that attach the oil filter heat shield to the engine. The removal of this piece will aid with the removal of the factory exhaust manifold and installation of the new header.

The re-installation of the heat shield is optional.

Remove the factory exhaust manifold from the engine.

Please do not throw away your factory exhaust manifold. Re-use the gasket if there are no signs of damage or wear. Replace if necessary.

Prepare the o2 sensor for removal with penetrating oil.

Remove the primary o2 sensor from the catalytic converter pipe.

Install the o2 sensor in the first port closest to the flange that attaches to the engine.

Depending on the mileage of your vehicle, it is recommended to inspect your primary o2 sensor for possible replacement.

Remove the 10mm bolt attaching the bracket for the primary o2 sensor harness and remove the clip to detach the harness from the bracket.

Cut the next clip up that attaches the o2 sensor wire to the firewall.

This will need to be removed to get slack out of the wire for the o2 sensor to reach from the header to the harness.