This is something that comes up all the time. I get PMs from people asking for information in regards to part numbers and other aspects of exhaust part installation. So, here is a thread with all sorts of information in regards to exhaust parts.
This is for all the DIY people out there... you will do a much higher quality job if you follow the specs below.
Downpipe-to-catback torque spec...........13.0 ft-lbs
Axle-back torque spec ..........................35.4 ft-lbs
Exhaust bracket torque spec ..................26.0 ft-lbs
Transmission bracket torque spec ............26.0 ft-lbs
Downpipe-to-midpipe torque spec ............26.0 ft-lbs
Downpipe-to-turbo torque spec .............. 26.0 ft-lbs
Uppipe-to-turbo torque spec ...................26.0 ft-lbs
Turbo bracket @ up-pipe torque spec .......26.0 ft-lbs
Turbo bracket-to-block torque spec .........24.6 ft-lbs (highly unlikely you will need this one.)
Head-to-manifold torque spec .................29.8 ft-lbs
Manifold-to-crossover pipe torque spec .....26.0 ft-lbs
Manifold-to-uppipe torque spec ...............26.0 ft-lbs
Manifold heatshield torque spec ...............9.6 ft-lbs
Front 02 sensor torque spec ...................22.1 ft-lbs
Rear 02 sensor torque spec ....................15.2 ft-lbs
Intercooler-to-turbo flange torque spec ....11.6 ft-lbs
Intercooler brackets torque spec .............11.6 ft-lbs
By-pass valve-to-intercooler torque spec .. 4.8 ft-lbs
In addition, here are the part numbers for all the exhaust gaskets too.
Head to Exhaust Manifold Gaskets - 2 are required to replace in case you install a header.
Driver's Exhaust Manifold to Crossover Pipe gasket
Crossover Pipe to Pass Exhaust Manifold Gasket
Exhaust Manifold to Uppipe Gasket
Uppipe to turbo Gasket
Turbo to Downpipe Gasket
Downpipe to Midpipe
Flex Joint Gasket (the donut)
If you guys want, I might also include a how-to on UP/DP installation, but frankly, those are a dime a dozen on WRX sites..
Installing Exhaust Gas Temperature Sensor
- 14mm wrench (possibly 2)
- 14mm socket
- 12mm socket
- 1/8" NPT tap
- Various drill bits (11/32, small drill bit for pilot hole, big drill bit for possible hole on heatshield)
- Dremel (optional - for heatshield)
- Panel popper or flathead screw driver
- PB Blaster or equivalent penetrating lubricant
- The routing of the harness is entirely up to the end user.
- A good place to install the sensor is in the “button” of the driver’s side exhaust manifold.
- During more recent testing, it has been shown that the driver’s side of the engine runs higher EGTs than the passenger’s side.
- Carefully lift the front of the car and secure using jack-stands.
- 5. Remove belly pan. There are 3 12-mm bolts in the front and 1 in the rear. There are also 2 plastic tabs on each side of the pan, for a total of 4. There are tab removers available, but a flat head screwdriver will work if one is not available.
- Remove driver’s side exhaust manifold heat shield. This is secured by 3 12-mm bolts.
- Remove the 2 14-mm bolts in that hold the manifold to the crossover pipe. Hold on to that gasket. You will need at least one open-end wrench for this, but two are useful. Ratchet type open-end wrenches are the best.
- Remove the 3 14-mm nuts that hold the manifold in place.
- Locate the little button in between the No. 2 and No.4 exhaust pipe.
- Drill a pilot hole in the middle of the “button”.
- Drill a hole using a 11/32” drill bit. Make sure to use some type of lubricant to cool and help out the bit. Also, regulate the speed so that you can cut into the metal more efficiently. Faster really is not better here.
- Start to tap your thread using the 1/8” NPT tap. Get some help for this as it requires some incredible amount of force. It is typically not recommended to back out of the thread very often when using a NPT tap. And when you think you have gone far enough and hard enough, back it out, clean the threads, and go again a little harder until it REALLY is impossible.
- Clean the threads and the interior of the manifold to remove metal shavings.
- Install the fitting. Use discretion when torquing it down.
- If you plan on re-using the heat shield, do not install the sensor just yet.
- Mark the heat shield in the appropriate location and use either a HUGE bit (bigger than 3/8”) or use a dremel to obtain the desired size.
- Install the manifold back to the engine and crossover pipe. Do not forget the gasket!
- Install heat shield.
- Install sensor. Do not over-tighten.
- Plug sensor harness.
- When starting the car, you might experience some smoke due to the lubricant used during the drilling process. Other than that, check for leaks.