DIY O2 Sensor/cat removal without removing cowl

[iWANNAsiR]

I removed the stock down pipe and O2 sensors and installed the new Skunk2 downpipe without removing the cowl or anything else. The only tools I used were a deep well O2 sensor socket, a standard Craftsman 3/8 ratchet handle, and standard Craftsman sockets. No deepwell sockets or extensions were used. I only used jackstands.
My process was:
-Remove the exhaust and lower cat
-Remove the 2 lower 12mm bolts from header flange
-Remove the 3 12mm bolts from the heat shield
-Unplug and remove the 7/8in O2 sensor
-Remove the 2 12mm nuts from the header flange
-Remove the 2 14mm bolts and the bracket that secures the cat to the block
-Turn the cat up-side-down and the header flange facing toward the rear of the car
-Be patient and negotiate the cat straight down it will fit between the axel and the subframe (It was very tight on an OEM Honda oil filter so if you have something larger it may get in the way)
-DO NOT force the cat out it will come out, however it is tight.
Tools that I used
View looking up the rust is the axel
Aview looking front to back
More tools I had at my disposal, but weren't used
There is plenty off room up there for everything
For reinstallation a 1-3in extension and 12mm wrench may make the flange bolts/nuts easier

 

[Jasdeep Badwal]

I removed the stock down pipe and O2 sensors and installed the new Skunk2 downpipe without removing the cowl or anything else. The only tools I used were a deep well O2 sensor socket, a standard Craftsman 3/8 ratchet handle, and standard Craftsman sockets. No deepwell sockets or extensions were used. I only used jackstands.
My process was:
-Remove the exhaust and lower cat
-Remove the 2 lower 12mm bolts from header flange
-Remove the 3 12mm bolts from the heat shield
-Unplug and remove the 7/8in O2 sensor
-Remove the 2 12mm nuts from the header flange
-Remove the 2 14mm bolts and the bracket that secures the cat to the block
-Turn the cat up-side-down and the header flange facing toward the rear of the car
-Be patient and negotiate the cat straight down it will fit between the axel and the subframe (It was very tight on an OEM Honda oil filter so if you have something larger it may get in the way)
-DO NOT force the cat out it will come out, however it is tight.
View attachment 41028Tools that I used
View attachment 41027View looking up the rust is the axel
View attachment 41030Aview looking front to back
View attachment 41029More tools I had at my disposal, but weren't used
View attachment 41031There is plenty off room up there for everything
View attachment 41032For reinstallation a 1-3in extension and 12mm wrench may make the flange bolts/nuts easier

Did you use the stock gaskets and everything that came with the skunk2 downpipe because I read reports of leaking, did you experience any of that after installation? Thank you for your DIY tho very helpful.

 

[iWANNAsiR]

I use stock head to manifold gasket and I used Skunk2's lower gasket. So far so good as far as gaskets go.

 

[Jasdeep Badwal]

I use stock head to manifold gasket and I used Skunk2's lower gasket. So far so good as far as gaskets go.

I just installed it 2 days ago and there's this annoying rattling, like metal on metal sound, I guess it kinda sounds like a buzzing sound too kinda hard to describe, but have you experienced any of that?! I don't really know if it's normal or not, I have the stock exhaust but an axle back straight pipe, please help!

 

[iWANNAsiR]

The Skunk2 DP makes a noise for the first 30 seconds after start-up. From what I understand it is kinda normal with the DP. As fas as what you are asking about, it sounds like something maybe loose/rubbing.

 

[Tom's Si]

My Skunk 2 broke at the first weld. Replaced it with a Buddy Club DP. Removed and replaced without the cowl removal. Thanks for the tip/DIY.