Just finished installing catted PPE downpipes on my car. I didn't plan on creating a how to guide, so I did not take any pictures or really make any effort to record the process. Afterward though I got to thinking that there's not a how to floating around that I'm aware of for this task.
So, this is a poor excuse for a how to guide, but maybe it will help someone at least decide if they want to tackle the job and help them know if they have the tools needed. I don't think there's a specific order that things need to be done and I don't think pictures would aid much as everything is fairly visible once you dig in.
I did the job in my garage with the car on jack stands using hand tools. This was the first time even seeing the underside of my car, so I just dug in and went to work. I'm sure you could do the job in any order with multiple different tool options, but here's what I used and the steps that I took...
Minimum Required Tools:
Jack and 2 stands
½" drive socket wrench
½" drive breaker bar – unless you are stronger than I am and can just use the wrench
½" universal – make sure you have a good one
½' extensions – need an assortment of lengths
½" 15mm socket
15mm wrench
17mm socket and wrench if installing PPE downpipes (others may come with different bolts/nuts for the rear exhaust connection)
7/8" open end wrench or O2 sensor socket/tool
Steps I took to replace the factory down pipes with aftermarket pipes (most of the steps can be done in any order):
1. Disconnect battery
2. Loosen lug nuts on front passenger wheel
3. Jack up front of car and put on stands. The higher the better and be safe!
4. Remove front passenger wheel
5. Crawl under car and remove the access panel.
6. Use PB Blaster to spray EVERY bolt related to the job. This includes all 6 turbo stud/nuts, 4 O2 sensors, 4 nuts that bolt down pipes to the exhaust by the third catalytic converter. Do not spray or remove the nuts on the intermediate pipes. Those can be left alone and removed with the down pipes.
7. I paused overnight at this point to let the PB blaster soak in.
8. Unplug front primary O2 sensor, disconnect from bracket, and remove from wire hold tab. Access from top.
9. Unplug rear primary O2 sensor and disconnect from bracket. This one is hard to access. I got to it from the top. It is on the passenger side rear of the engine compartment and is fairly deep.
10. Use the 7/8" open end wrench to remove the front primary O2 sensor. I could not find my O2 sensor socket, but it would not have been any better. The wrench worked fine and was fast. This is the only O2 sensor that requires removal if you have a non-PP car. I suspect that a PP SHO would need the primary rear O2 sensor removed to clear the cooling system.
11. Unplug the two secondary O2 sensors.
12. Use the 15mm socket and ½" drive tools to remove the nuts that hold the downpipe to the rear turbo. They are accessed through the passenger side fender well. Universal is mandatory. I also needed a breaker bar as I didn't have access to a gorilla.
13. Use the 15mm socket/drive and a wrench to remove the nuts that hold the rear downpipe to the exhaust by the third catalytic converter.
14. Wiggle, jiggle, twist, turn, and tug the factory downpipe until it comes out. It WILL come out complete with the O2 sensors in place (on a non-PP car) and with the intermediate pipe attached. Just be patient and keep looking at the O2 sensor through the wheel well and keep twisting.
15. Use the 15mm socket and ½" drive tools to remove the nuts that hold the downpipe to the front turbo. They are accessed from under the front of the car by the oil filter. Universal is, once again, required. You can gain better access to one of the nuts by removing the oil filter. It was not time for my oil change, so I worked around the filter, but did dent it in the process. Probably best to time the oil change if possible.
16. Use the 15mm socket and 15mm wrench to remove the nuts that hold the front downpipe to the exhaust by the third catalytic converter.
17. Remove front downpipe from vehicle.
18. Remove remaining 3 O2 sensors from the two downpipes that are now removed from vehicle.
19. Install 3 O2 sensors into replacement downpipes in the same locations. Keep the Primary front O2 sensor to the side for installation later.
20. Put new or used gaskets on the two turbos. I chose to replace these gaskets, but my factory ones looked just fine. I could have reused them.
21. Twist, thread, push, and pull the rear new downpipe into position and line up the flange with the studs on the turbo. Re-install the nuts with 15mm socket and tools, but leave barely loose.
22. Bolt the new rear downpipe to the exhaust using supplied hardware and a new or used gasket, but leave slightly loose. My downpipes came with 17mm bolts and nut.
23. Install front downpipe (minus the primary O2 sensor) by lining up the flange with the 3 studs on the turbo. Install the nuts, but leave slightly loose.
24. Bolt the new front downpipe to the exhaust using the supplied hardware and a new or used gasket, but leave slightly loose.
25. Eyeball the two downpipes and wiggle/move them until they are even in the rear.
26. Tighten the front and rear downpipes to the turbos. I'm sure there is a proper torque spec. I went with as tight as I could get them using my ½" drive socket wrench.
27. Use the 7/8" open end wrench to install the front primary O2 sensor.
28. Tighten the exhaust hardware that connects the downpipes to the exhaust by the third catalytic converter.
29. Plug all 4 O2 sensors back into their connectors, remount them to the holders, and make sure the factory wiring locations are retained.
30. Jack the car up, remove the stands, and safely lower the car.
31. Reconnect battery.
32. Start car and give it time to relearn idle and to burn off the PB Blaster residue. I had very little smoke.
33. Take the family to a late lunch and show them how the car comes into boost sooner and runs harder
Please feel free to chime in with ANY suggestions for improvement. I am NOT a mechanic and do not have ANY problem with anyone that would like to correct any of my mistakes. The only picture that I can think of that would be of much value would be the rear primary O2 sensor connector location. Glad I had on Mechanix gloves for that one cause you just have to dive in fairly blind.
Special thanks to my wife that provided needed moral support and did a fair amount of wrench turning. Plus she helped me off of the garage floor multiple times!
