DIY How to install a RV6 2012+ Civic Si Bellmouth Downpipe

Arm0ged0n

Arm0ged0n

Well-Known Member
1,591
1,505
Lake Elsinore, CA
Vehicle Model
Honda Civic SI
Body Style
Sedan
Hey Ladies and Gents,

Just like I promised, here's the DIY for the downpipe, enjoy :)


D.I.Y. Install for RV6 Downpipe for 2012 Civic Si Sedan
This article will cover the install of the RV6 downpipe ONLY. I will not cover on how to remove the cowl. If a D.I.Y. is needed on how to remove the cowl, then I will cover that next time (but as a tip, you will need to completely remove the windshield wipers to remove the cowl). Last, but not least, I am NOT RESPONSIBLE for any damages you may cause to your car. I was very careful in doing this myself and caused no damage to the vehicle or parts. DO THIS AT YOUR OWN RISK. Do not be stupid and you will do fine. Remember, having the right tools will make your life so much easier. Do not try to take shortcuts. You have been warned. As a useful tip, read through this entire article once before starting, that way you know what you’re getting into. Set aside anywhere from 2-5 hours for this job. If you got the skills and extra tools, this could easily be done within an hour and a half.

Tools needed:
· 3/8” socket wrench
· 1/2” socket wrench
· Various lengths extension bars for both socket wrenches
· O2 Sensor socket (will need to be filed down)
· 10 mm, 12mm, 14mm, and 17mm sockets
· 17mm combination wrench
· Jack with jack stands.
· Patience
· Elbow grease.

Optional tools:
· Breaker bars
· Pick (helped for removing the rubber hanger)
· Screwdrivers (also for removing rubber hanger)

1_G.jpeg




Procedure:
1. First remove the cowl. As mentioned before, I will not cover how to remove in this section. It helps to tape or mark the position of the wipers because you’ll have to remove them to get the cowl off. As a tip, the wipers are operated by a gear, so each notch of that gear has its own position. This is why you need to mark the location of the wipers. If you had trouble removing the wipers like I did, then you can try to wiggle it back and forth with wipers in the up position.

2_G.jpeg




1. Secondly, you will need to remove the O2 sensor from the top of the downpipe. Remove the plug before unbolting the O2 sensor. There is a cup surrounding the nut of the O2 sensor which is why we needed to file down the O2 sensor socket to get it to fit.



3_G.jpeg



The O2 sensor with the cup at the base

4_G.jpeg


The O2 sensor socket that we had to grind down.

5_G.jpeg



O2 sensor removed.
Next remove the three 10mm bolts on the heat shield and remove the heat shield. You will have to twist and turn the heat shield around to get it to fit out. The three 10mm bolts can be seen in the picture with the O2 sensor still bolted to the stock downpipe.


1. Now loosen the two top 12mm nuts and remove the two lower 12mm bolts from the downpipe. You want to keep the two top 12mm nuts on so you don’t drop the downpipe piece on your face when you’re working on it from below the car. Keep the 12mm bolts, we’re going to reuse them (same with the 12mm nuts, but it’s going to be on there until the end anyways).

6_G.jpeg



Jack up the car and place jack stands where appropriate (we placed them at the sides near the front doors). Unplug and remove the secondary O2 sensor from the catalytic converter (green wire in the picture). Set this sensor aside for reuse. Now remove the catalytic converter hanger from the rubber piece (not the hanger that’s attached to the car itself). I found inserting the pick all the way through the rubber piece and using the hanger as a fulcrum point to pry the rubber piece off of the hanger. The rubber piece seems to sustain itself very well and did not tear or rip when I tried this

7_G.jpeg
​
​
​
We’re going to disconnect the downpipe from the catalytic converter. There are two 14mm (can’t remember if it’s 14mm or 12mm) spring bolts and they’re a ***** to get a good angle to work at to unbolt them. Furthermore, the nuts they bolt into are welded nuts, so you can’t remove from that end (unless you want to impact drive that out). Also, they’re SPRING bolts, so there is going to be tension on these two bolts until you sufficiently drive them out of the welded nut. What that means is that you might get a little bit tired and a lot of elbow grease is going to be required. Honestly, this took the longest part
​

1
 
8_G.jpeg



1. We are going to disconnect the catalytic converter that’s connected to the mid-pipe. There are three 14mm nuts on this piece that is also a bit of a pain to remove. It’s on there HARD. I listed the breaker bars as optional because they proved to be helpful here. If you have a breaker bar, jack up the car as high as you can to get some clearance and muscle those three nuts off. Be careful of the heat shield that surrounds the pipe (it’s connected to the car itself). It bends easily. Once you loosen the nuts off, remove the catalytic converter and set it aside.​
​
9_G.jpeg
​
1. Next step is to remove the bottom heat shield on the downpipe. There are four 10mm bolts holding it in. You’ll access the top two from the engine bay top, while the bottom two will be accessed from below the car. I don’t think pictures are needed for this step.​
​
2. Time to remove that downpipe! We just need to remove that bottom bracket that supports the downpipe. You can see this bracket in the picture I supplied with in Step 6. I believe that is a 17 mm bolt. At the other end of the bracket is another 17 mm bolt. They’re not on there too tight, so don’t try to go Super Saiyan on those two bolts. Remove the bracket and set it aside. Now remember those two nuts I told you to leave on at the top of the downpipe? That’s what’s holding this thing on. The downpipe itself is VERY light, but is rather large so handling and removing it is a bit of a bother. Either get a friend or risk the downpipe hanging onto the studs when you remove the two nuts. You’re going to have to shimmy, twist, and turn to get this thing out. It’s not too hard. Once you find the angle, it comes out without even hitting anything around it. If you take a second to look around that area, you’ll find how to get it out. This literally took me all but two minutes.​
​
3.Before we can install the RV6 downpipe we need to clean the mounting surface of the downpipe to the headers. The kit should’ve provided you with a new gasket which we used (we could’ve easily reused the old one though) and the kit should’ve given you a copper gasket to go on the mid-pipe end. Keep in mind the direction of the gasket. I’m not sure if the direction truly matters, but keep things consistent people.​
​
10_G_001.jpeg
​
​
​
The mounting surface cleaned and next we apply the metal gasket provided in the kit.​
​
11_G_001.jpeg
​
​
The side that is FACING YOU in the picture is the side that touches the DOWNPIPE. Notice it’s two-pieced with a rivet connecting them. Not the greatest picture, but hopefully a decent reference.​
​
Finally we can install the RV6 downpipe! We had the catted version, but I don’t think the install will differ much. This is actually VERY EASY to install. The damn thing is so nicely curved with less bulk than the stock downpipe and cat that it pretty much just needs to be angled in correctly. The RV6 has a flex part to it that makes install go extra smooth. Install to the headers first reusing the two 12 mm nut and bolts that we originally had on. Then install the cat end using the nut and bolts that the kit provided. The washer and lock washer should be on the bolt end, not the washer end. I do not have the torque specs nor do I believe you need to torque them down to specs. Just tighten them and don’t be a dumbass and go over-tightening everything​
​
 
12_G_001.jpeg


1. Reinstall the hanger to the downpipe, the two O2 sensors to their respective locations as well as plug them in, and reinstall the cowl. The heat shields aren’t going to be reused.

2. Also important, start up the car and let the car idle for 10 minutes. The ECU needs to register the new dynamics of the exhaust and input that into its database. Don’t be an *** and go revving off as soon as you start up the car for the first time after the install.

3.After ten minutes, go out and have some fun! If the CEL light turns on, it’s because you have incorrectly reinstalled the O2 sensors or forgot to plug them in.
 
Just curious if you happen to still have that ground down o2 sensor tool. If so i need to borrow that soon. I have a downpipe on the way.
 
squiggy said:
You can go to an auto parts store and get a socket style O2 sensor removal for about $10. I used one last weekend no problem.
Click to expand...
+1 same here did mine last night with the socket O2 sensor remover, fit like a glove no filing.
 
Last edited:
Arm0ged0n said:
3.After ten minutes, go out and have some fun! If the CEL light turns on, it’s because you have incorrectly reinstalled the O2 sensors or forgot to plug them in.
Click to expand...

What do you mean by installed incorrectly? Just flipped locations? A little hard to do that considering the cowl/heat shield on the upper sensor.
 
Last edited:
Good right up. For what it is worth I removed the stock down pipe and O2 sensors and installed the new Skunk2 downpipe without removing the cowl or anything else. And 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 used two jackstands on the passenger side, the drivers side was on the ground.
 

Attachments

  • IMG_4128.JPG
    IMG_4128.JPG
    1.3 MB · Views: 59
  • IMG_4137.JPG
    IMG_4137.JPG
    2.8 MB · Views: 59
Last edited by a moderator:
Please don't hijack DIY threads. Start a new one if you think you have something different to contribute. Also, two jack stands on one side of the car is DANGEROUS!
 
Not trying to jack a thread... I was just trying to save people hours of work for nothing. Removal/install took me less than 45 min.
 
You must log in or register to reply here.
Back
Top