(Its long I know but its pretty step by step installation since one doesn't exist.)
The removal of the heat shroud and brace bar was pretty easy. I placed the windshield wipers up to make it easier to remove the shroud. The heat shield on the stock headers was next to go(3 bolts), it pulled out from the bottom with some serious finangling. Remove both 02 sensors. The primary 02 sensor needs to have the wires extended, you should remove the bracket for the wire also. I ran my wideband sensor and placed it where the secondary 02 would normally go. Install the 02 sensors as the last step. The two spring bolts were removed from the header. One sheered right off so plan to have replacements ahead of time. Skunk plans on you reusing these, good idea dumbasses. Remove the three bolts going into the exhaust. Pulled out the cat. Remove the 3 bottom bolts and the two top nuts on the header. There is a bracket running down in front of the steering rack that attaches to the stock headers. The bracket needs to be loose to get the header out. The header had to be turned so the engine side is facing down and the pipe bend are facing up to get it out. I recommend removing the bracket that secures the shift linkage to give you more room. Remove the bracket for the stock exhaust too, you will have to remove the shield for the steering rack to get the bolt out for the bracket. Insure you replace the manifold gasket. Place the skunk2 headers in upside down. Once you clear the two brackets spin the headers around and feed them up slightly. Place the shift linkage brackets back on before feeding them the whole way up. Place the headers into position and place the supplied bracket where the two wire supports are for the 2nd 02 sensor, do not over tighten these. Take the exhaust rubber grommet of the stock cat to use on this bracket. Place a EP3 donut gasket over the header side of the spacer. Place the bolts back into the engine for the manifold, and place the original/new bolts in the supplied spacer to mate the exhaust and headers. You should use a new pinch gasket for the spacer and exhaust. Do no tighten anything down. Lift up on the headers and tighten the manifold bolts first, this helps them from rubbing on the steering rack. Tighten the bolts on the spacer. The metal on the spacer will bend if you over tighten them on the header side. Insure the 02 sensors are installed, snug, and connected. Make sure to zip tie the wires away form the header. Reinstall the heat shroud and cowl above the engine. If you have Hondata, reflash the ecu and disable the secondary 02 if you are using a wideband.
Key points/Helpful hints:
-Purchase new bolts ahead of time since skunk2 doesn't send you any. The stock ones are very likely to sheer or be very very rusty.
-Purchase a donut gasket for a stock EP3 civic or S2000. The one provided by skunk is almost guaranteed to leak. Purchase a new pinch gasket for the spacer and exhaust mating. I used a vibrant one.
-Purchase a new exhaust manifold gasket.
-Remove the shift linkage bracket to give you more room during the install.
-Start the car on a lift and check for leaks.-
-The heat shield and stock headers are a bitch to get out, be prepared to be patient.
-Hit all the exhaust bolts and header bolts a day ahead of the install with pb blaster, it will help.
Review
The headers look awesome. The install was relatively easy after the stock parts were off. Skunk2 really needs to up their quality though. The header should have came with instructions.It should have come with a decent donut gasket that doesn't leak. It should come with replacement bolts for every bolt on the exhaust, and they should give you a header gasket. They could even charge $50 extra, at least you wouldn't have to go search for bolts for a $450 header you just bought. For this reason I will not buy another skunk 2 product. The engineers make good products but they don't use there heads when it comes to the final product to give to a consumer. Quality or quanity skunk2.
Once the install was completed I reflashed the ecu with hondata's CAI, skunk2 header, and skunk2 exhaust calibration. I took the car out for the test drive. The headers make the exhaust alot louder in a good way, but the vibrations really aren't that bad at cruising speed. Once I put the pedal down the power increase is defiantly noticeable. There is a dramatic increase in torque and power in the low and mid range. There is a noticeable increase in high end power too. The engine responds alot quicker coming on and off open throttle. The CAI, exhaust, headers, and hondata net a 30whp increase in power from stock. I am very pleased with the sound and power increases, the exhaust defiantly lets the engine flow better. I highly recommend this header as an upgrade.
