DIY Full-Race 3" Downpipe and Catback Exhaust System

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Super Mod
11,183
6,654
Michiana
Vehicle Model
'12 Civic Si
Body Style
DBP II Coupe
Parts Needed:
Full-Race Downpipe (catted or catless)
Full-Race Exhaust
2 gaskets (supplied)
6 bolts (supplied)
6 lock washers (supplied)
6 nuts (supplied)
Clamp with adjusting bolts (supplied)

Optional Parts
Rear Motor Mount - highly recommended, but not absolutely necessary

Tools Needed:
Jack
Jack Stands
3/8" Ratchet
1/2" Ratchet
1/4" Ratchet
Torque Wrench
Various Extensions
10-19 mm Sockets
9/16" Socket
O2 Sensor Socket
WD-40, Liquid Wrench, or Grease of choice.
Masking Tape
Trim/Clip Removal Tools
Rags
High Temp Anti-seize

Disclaimer: I do not have torque specs. Use your best judgement.

Step 1:

You can do this a few ways.

1. Use a lift.
2. Put your car on jack stands.
3. Lift the front and rear of the car as necessary. Not recommended as this would be a hassle, but doable if it is your only option. Make sure to use some wheel chocks if you chooses this method.

Step 2:

Cowl Removal - You will need to mark your windshield wiper placement with masking tape in order to make sure you get them back on in the correct position. I also marked the left one with a piece of tape since the wipers are different sizes.




Next, you will need to do is remove the caps to the nuts on the windshield wipers. You can use a screwdriver or one of the trim piece removal tools. They are pretty simple to wedge off.


The plastic piece that covers part of the nut can be unclipped as shown by the arrows below. It doesn't come off completely, but will move out of the way. You may want to do this with the hood up, but is possible with the hood down as it gives just enough room. The nut is 17mm.



I am missing pictures for removing the upper pieces of the cowl on the left and right, but they do pop out. Although not as easily as you would expect.

There are three plastic clips that need to be removed as shown below. The clip removal tool or a plastic trim piece removal tool works best, but you could manage with a flat head screwdriver if necessary.





The cowl has a small hose for the windshield washer fluid attached it on the passenger so car must be taken when removing it. I simply laid the entire cowl piece off to the side on the passenger side of the engine bay.


To be continued in the next post...
 
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Super Mod
11,183
6,654
Michiana
Vehicle Model
'12 Civic Si
Body Style
DBP II Coupe
Step 3: Heat Shield Removal

After removing the cowl, what I assume is a heat shield will need to be removed. There are three 10mm bolts in the locations as shown below. Take care when removing these as they are small and you may drop them since they are inset and not easily reached with a normal size hand! Don't mind the nut that was removed from the top of the strut. That was a mistake in the learning process.



[



Next, you will remove the the three bolts on each side that hold the heat shield onto the top of the wheel wells. These are 10mm or 12mm. Again, don't mind the nut that was removed from the top of the strut. That was a mistake in the learning process.



Now you can remove the heat shield and set it off to the side on the floor. You will now have access to the top of the down pipe.

To be continued in the next post...
 
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Super Mod
11,183
6,654
Michiana
Vehicle Model
'12 Civic Si
Body Style
DBP II Coupe
Step 4:

Remove the O2 sensor (above arrow) from the top of the downpipe. You will need to locate the clip as shown (kinda) in the circle below. This is a tight fit and you may need to try and find a few different angles. This must be removed before trying to take the O2 sensor out.


You will need the O2 sensor socket to remove the O2 sensor. Be very careful of the wires!!! If you sever any of them, you will need to buy a new one. It is possible to reach the O2 sensor from two different angles. Either squeezing the ratchet sit sit right down on top of the O2 sensor or using an extension to go down through the cutout as shown below.

Be very careful with the O2 sensors as to not damage them. I found a little box to put mine in and set them on a clean rag.


Step 5:

Now you will need to remove the upper down pipe heat shield in order to be able to access the nuts and bolts that hold the downpipe onto the engine. These are 10mm and can be seen below.


Step 6:

Remove the 2 nuts and two bolts that hold the downpipe to the engine. These are 12mm. Two of nuts and one of the bolts can be seen below. For the fourth one, you will need to feel around and possibly use a deepwell or an extension.


Step 7:

Removal of the downpipe support bracket connected to the engine block. There are two bolts and they are 12 or 14mm. This bracket is not needed to install the Full-Race downpipe.


Step 8:

Remove the lower O2 sensor from the mid-pipe. I do not have pictures of this, but it should be simple enough. As stated above for the upper O2 sensor, make sure to unclip the wire first!!! Follow the wire up to the connector and disconnect it. I found it difficult to do this without removing the bracket that the wore is connected to. See the picture below for a shot of the bracket. It is connected with a single 10mm bolt.



Step 9:

Remove the mid-pipe. The mid-pipe is actually two pieces. There is a short one that comes off the bottom of the downpipe where the cat is and another one with the resonator that connects to the muffler at the axle. See pics below.



I started with the smaller piece coming off of the downpipe/cat. There are two 12mm spring bolts. There is no need for a second wrench as the flange is threaded. These may need penetrating oil.


There are an additional 3 bolts on the rear portion. They are 12 or 14mm. You will want to douse these with your penetrating oil of choice multiple times. These bolts are a royal pain to get off!!! I used a cordless impact wrench without any luck. If you are on a lift, a breaker bar should work. Then again, if you are on a lift, you probably have access to a pneumatic air ratchet.


To be continued in the next post...
 
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Super Mod
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Vehicle Model
'12 Civic Si
Body Style
DBP II Coupe
Step 10:

If you managed to get the smaller mid-pipe off, you can now remove the the rubber hanger from the car that holds the pipe in place. You may want to spray some lubricating oil onto this first. You can leave the hanger on the pipe for now.


Step 11:

You can now remove the downpipe from the engine. This task is a bit of puzzle. Laying under the car, grab the cat and slide the whole thing towards the rear of the car to clear the studs that connect it to the block. You will need to twist and turn it in various ways until you find one which works. I assure you that it will come out though. There is a metal gasket between the downpipe and block. It may stay stuck to the block or the downpipe. You will need to reuse the gasket!!!

Step 12:

Remove the second portion of the mid-pip. This is connected to the muffler by two additional spring bolts and are threaded through the flange. They are 12mm. You may need penetrating oil.


Once the bolts are removed, you will need to remove the hanger from the car located at the bend. This one should come off fairly easy, but may need some lubricating oil. You can leave the hanger on the pipe for now. Sorry for the funny angle of the picture.


Step 13:

Remove the muffler. The muffler is connected to the rear of the car by a rubber hanger located above where the tip meets the main portion of the muffler. Douse it with penetrating oil and remove it from the single prong connected to the car. You can keep it connected to the muffler for now.


Step 14:

Transfer the rubber hangers to the Full-Race downpipe and exhaust. It would be best to use some sort of grease as opposed to the lubricating oil for this as it will allow some play when putting everything on and aligning it.

Step 15:

Install the downpipe. Locate the gasket and put it on at the engine block if it is not there still. From underneath the car, feed the downpipe up and attach it to the engine block. This is a lot easier to do than removing the stock downpipe.


Once you have it sitting in place against the engine block, you can attach the rubber hanger. You can also reinstall the O2 sensor. It is recommended, but not required to put the anit-seize on the O2 sensor threads. The wire is a bit tight and will just float in place. I made sure to run it as shown below to make sure it doesn't potentially snag anywhere. If you removed the plate when removing the O2 sensor as I suggested above, make sure to reinstall it now.


The steps for reconnecting the upper O2 sensor and downpipe bolts to the engine block are at the end of the DIY!!!

Step 16:

Installing the mid-pipe. Using the supplied bolts, lock washers, and gasket, connect this small piece to the downpipe. You will need a ratchet and wrench to tighten these down. Here is the pipe I am referring to:


When installing it, make sure you pay attention to where the slight bend is in the pipe. You will want to make sure that it slopes downwards. There is no need to bend the heat shield as it clears it just fine.

<-----Rear of vehicle

Step 17:

Connect the resonator to the mid-pipe. The resonator will slide right over the mid-pipe. Make sure you slide the clamp on first. I found this connection to be a bit tight and rubbed a small amount of WD-40 on the edge of one of the pieces to make it slide together easier. Do not tighten this clamp yet in case you need a little bit of play when connecting everything else. (Ignore the fact that it is tightened in the picture already.)


Now connect the rubber hanger at the bend.



You may need to push the heat shield up a bit at this point. Be sure to check the clearance and decide for yourself whether or not you feel it may need to be bent.

To be continued in the next post...
 
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Super Mod
11,183
6,654
Michiana
Vehicle Model
'12 Civic Si
Body Style
DBP II Coupe
Step 17 continued:

Connect the rubber mount at the rear axle. This one is also a royal pain. Make sure it is greased up well as you may need to slide it to ensure clearance from the spring and part of the frame. When you first put the rubber mount on the Full-Race hanger, slide it on with about 3/4" of the metal showing on the outside end.


Clearance. Sorry about the angle, but that was the best I could do. It does clear the spring fine.


Step 18:

Mount the muffler. Make sure the rubber hanger is positioned with the word up (in the red box) correctly. When you slide the hanger onto the muffler, push them back about an inch. Grease these up well too as you will need to play around with positioning a bit.



Step 19:

Bolt the muffler to the resonator using the supplied bolts, lock washers, and gasket. You will need a ratchet and wrench. Due to space being tight, it is recommended that you put the head of the bolt towards the front of the car as shown in the picture below. Space is really tight for the bolt in the top circle. You will need to play around with socket depth and extensions to figure out what works best for you.



Step 20:

Tighten the clamp at the mid-pipe using a 15mm socket. You can position this in any way you want, but I choose to put the bolt at the top. This one needs to be tight. Use a breaker bar.





Step 21:

Tighten the 2 bolts and 2 nuts securing the downpipe onto the engine block. Three of them are circled. As with taking the stock downpipe off, you will need to feel around for the fourth one.



Step 22:

See picture above. Reconnect the O2 sensor. Again be careful with the wires and possibly anti-seize. After you have tightened it, don't forget to reconnect the clip.

Step 23:

Reattach the heat shield and cowl in reverse order of taking them off. When reattaching the small upper pieces of the cowl, be aware of the little blue clips (as seen below). Make sure they line up right with the slot (not shown).

View attachment 26831

Step 24:

Fire it up!

Take it for a drive. It will be really loud at first.

If anybody has any questions or something needs clarified, don't hesitate to ask. If anybody would like to provide correct sizes for the nuts and bolts, I would greatly appreciate it so I can update this DIY with the correct sizes.


Edit:

Some thoughts on having installed a Full-Race Downpipe and Exhaust

When I first installed both of these (at the same time), the only other modification I had was a resonator delete and K&N drop-in. I threw a CEL within 25 miles. I thought I was going to need an O2 defouler. I also had horrible rasp at moderate to heavy acceleration. Keep in mind this was on the stock tune. After I got FlashPro, I uploaded the ReFlash map and the CEL went away. The rasp was still there, though. Fast forward a few months and I installed an RBC, ZDX, and 3.5" SRI. I also loaded a basemap calibration (tune) geared towards my mods. No CEL was thrown AND the rasp went away...COMPLETELY. I believe the car was just not getting enough air. Even with the ReFlash, which also runs rich. This was not an ideal tune at all.

Lesson learned: To run this downpipe and exhaust, you need FlashPro and a proper tune! If you do not get a proper tune, you may throw a CEL and/or have horrible rasp depending on what mods you have installed.

Thoughts on sound

This was ear-splitting loud when I first fired it up in my garage. It breaks in fairly quick, though. Probably 500 miles or so and its tone will become stable. It has a nice deep tone and the drone is nearly non-existent when just cruising. Nice aggressive sound during acceleration. After using a proper tune, it got even deeper and sounds better!
 
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tommygunz904

tommygunz904

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67
37
jacksonville florida
Vehicle Model
civic si
Body Style
sedan
I don't know how I like the 2014 model. (even though i just bought a 13 sedan last month) Maybe itll grow on me. The only thing Im jealous about is the extra power, but if it is truly just from the exhaust then my already aftermarket exhaust will do just the same, right? let me know what you guys think....
 
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Cartographer
Super Mod
11,183
6,654
Michiana
Vehicle Model
'12 Civic Si
Body Style
DBP II Coupe
tommygunz904 said:
I don't know how I like the 2014 model. (even though i just bought a 13 sedan last month) Maybe itll grow on me. The only thing Im jealous about is the extra power, but if it is truly just from the exhaust then my already aftermarket exhaust will do just the same, right? let me know what you guys think....
Click to expand...

The extra few hp is nothing to be concerned about if you have replaced your DP and exhaust already. It would make no difference in the long run if you replaced both on the '14 anyway.
 
Jerod

Jerod

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70
11
Minot, North Dakota
Vehicle Model
'13 Civic Si
Lol so I used this DIY as a guide for installing my Skunk2 dp and exhaust. Pretty much the same except it took my inexperienced self about 6 hours. Great DIY though. Thanks!
 
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Cartographer
Super Mod
11,183
6,654
Michiana
Vehicle Model
'12 Civic Si
Body Style
DBP II Coupe
Jerod said:
Lol so I used this DIY as a guide for installing my Skunk2 dp and exhaust. Pretty much the same except it took my inexperienced self about 6 hours. Great DIY though. Thanks!
Click to expand...

Yeah, it probably took me around that long, but I didn't have a DIY to follow and I was documenting the whole thing in order to put up a DIY.
 
chacky09

chacky09

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113
23
Fort Irwin, Ca
Vehicle Model
Civic Si
Body Style
Sedan
im looking at my 2013 and do I really need to take the windshield wipers off. cause it looks like the same concept as the 8th gen and u didn't have to remove them
 
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Cartographer
Super Mod
11,183
6,654
Michiana
Vehicle Model
'12 Civic Si
Body Style
DBP II Coupe
chacky09 said:
im looking at my 2013 and do I really need to take the windshield wipers off. cause it looks like the same concept as the 8th gen and u didn't have to remove them
Click to expand...

You absolutely have to take off the windshield wipers to install ANY downpipe on a 9th gen Si.
 
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