Installation of my Cattman Y-pipe

This disclaimer to state that I will not be responsible for any damage or harm suffered by anyone who follows my installation procedure. This is just how I did it and is by no means the correct or recommended way to install a y-pipe. ANY USE OF THIS WRITE-UP AS A GUIDE IS AT YOUR OWN RISK.

1. I used a pair of 2 and 1/4 ton jack stands which gave me (barely) sufficient space to work under the car. Disconnected the negative terminal of the battery and ensured parking brake was engaged.

2. Used 10mm socket wrench to remove bolts holding the heat shield that was in place.

3. Removed O2 sensor using an adjustable wrench and placed it on the inside of the front splash guard. I put this as far away as the wiring would allow me so that it would not get accidentally damaged during the install.

Removed 2 silver bolts holding the y-pipe bracket, they are the ones pictured (right), above the O2 sensor bung on the chassis.

4. Sprayed Liquid Wrench on nuts and bolts on the front manifold, rear manifold, and main cat.

5. Used 14mm deep socket to remove bolts from front manifold to stock y-pipe.

6. Used 14mm socket to remove nuts from rear manifold to y-pipe. This is basically the flanged part of the y-pipe that is pointing straight up.

7. Used 12mm socket to unscrew the bolt that holds the y-pipe to the hanger.

8. Used 14mm deep socket to remove nuts from the main cat to the y-pipe. Please note that I actually took the car to Meineke to have them torch the original nuts off and replace them with new ones before I did the y-pipe installation. The main reason for this is that the original nuts were so badly rusted on and bolts are welded to the cat. With all the rust, the bolts are likely to snap if you try to force them off.

Replaced gasket with new gasket from Nissan.

9. Pulled the stock y-pipe off and here it is with the Cattman y-pipe (courtesy of D. Honey aka Fezzik).

10. Cut the O2 sensor wires and soldered extensions to them. I used 20 gauge wires for the extensions. There are 4 wires to be extended, 1 black, 1 gray, and 2 white. I made sure to distinguish between the 2 white (since I used only one color for the extensions) before cutting them so I could extend them to the corresponding white wire on the O2 sensor.

Screwed the O2 sensor into the new y-pipe so that I wouldn't have to hold it as I soldered the wires back. I made my extensions long enough so that they reached from the joints in the original wiring to the O2 sensor, while it sat in the y-pipe on the ground.

Remember to slide 2 pieces of heat shrink on each wire BEFORE soldering the joint together.

Made sure to solder the corresponding colored wires back together, as well as the correct white wires. "Shrank" the heat shrink using a lighter; there should be a piece covering each joint in the wires. 2 joints per wire and 4 wires means you should have 8 pieces of heat shrink. Or if you're like me and forgot a couple, electrical tape for a couple of em.

11. Used a Dremel with a cutting disk to trim one of the bolts (maybe by about 3-4mm) on the main cat so that the y-pipe would slide on easier.

12 Put the y-pipe on; started from the front manifold flange, followed by the rear manifold, then the hanger, and finally the main cat end. I re-used most of the original hardware, and the original crush gaskets, except for the gasket between the main cat and the y-pipe.

13. Zip tied the extended wires in 2 places to keep them neat and to avoid entanglements with any road debris. Used one of the silver bolts (see bottom of step 3) from the stock y-pipe bracket and a loose zip-tie to secure the extended wires to the chassis. More pics of this to follow.

14. Y-pipe on the car. Better pics to follow.