I purchased the XTC 2.5" Downpipe with high flow cat from Cobalt Addiction. And since I did the install I figured i would write up a "How-To" since there isn't one.

I have to give credit to Randy Oaklief (owner of a 378whp cobalt ss/sc). He made sure I didn't screw anything up.

Before doing anything, make sure the vehicle is off, and has had at least an hour or two to cool down. The catalytic converter gets very hot, along with the valve covers and transmission, places you will touch while doing this install. This is a fairly simple process, so lets get started.

Tools needed:

Step 1:
Make sure vehicle is in park, with the e-brake on. Place blocks behind rear tires. Jack up front of vehicle. Use a jack stand on both sides of the vehicle on the uni-body frame rails.

Step 2:
Remove heat shield bolts (3 of them) with 1/2"wrench. Then seperate the O2 sensor harness.


Step 3:
Remove Pre-cat sensor with O2 sensor wrench or 20mm wrench.


Step 4:
Remove After-cat sensor. Be careful when removing the sensors, because they have a habbit of seizing up. My after-cat sensor, after about 4 full turns, would not go any farther, it would go back in, but not out. I had to remove the old downpipe with the sensor still in it. I then had to reroute a new connector and wire. (Lucky my dad works at a Chevy dealer, and I got the new part within minutes)


Step 5:
Remove Bolts connecting downpipe to cat-back exhaust, 15mm.


Step 6:
Place something under the stock downpipe to catch it when it falls loose. I used an extra jack stand. Remove bolts connecting downpipe to exhaust manifold.


Step 7:
I reused the gaskets that were already on there since my GMPP cat back and exhaust manifold were just installed less than 2 months ago. No leaks. I also installed the new downpipe with old hardware because nothing broke, and the stock bolts are of a stronger grade steel.

Final Product:


The new sensor. Notice the new wires are black, not blue.


And there you have it. My first write up. I did forget to do a before video, but I will update with an after video of the full exhaust sound.

 

pretty good the only thing differnt that i did was that i did not remove the heatshield. on the ss.sc there is no need to. also i unclipped the O2 sensor and had to bring it to an autoparts store where they placed it in a vice inorder to remove it. but worked just the same and love my dp.

 

Well I had to remove the heat shield because I couldn't access the sensor plug in the exhaust manifold. There really isn't a whole lot of room for a normal wrench against the manifold. That was the main reason I had to cut up my wrench.

So how was the write-up? Did I have good pics and info? Was everything pretty easy to follow? Does it look like it would help anyone?

 

isn't the downpipe larger than your exhaust?? (diameter??) just curios to know if it still all works out..

and the how to is great man!!

 

Even though the DP is larger than the exhaust, the flanges bolt up perfectly even. I checked a week ago, and I still don't have any exhaust leaks.

I have to borrow my buddies video camera in a couple days so I can get the sound of the exhaust.

Thanks,
Archie

 

where the downpipe connects to the header you get those bolts off from underneath the car or through the engine bay. i dont know if i can get to those bolts from underneath the car

 

you get them from underneath the car. I have an 05 ss/sc broke the 2 bottom bolts. thank God the top one came out fine. just waiting on my down pipe now

 

And it rises from the dead.

I am pretty sure he has gotten it by now... it was over 10 months ago.

I didn't have a car lift, I just used jack stands, so I got 2 from the bottom and one from the top.

 

man I wish peps would pic host these on css.net my work blocks all hosting sites. I have a way to get around them but takes like 10 mins to do it. any way Im sure I will be useing this when I decide to do mine GJ

 

u got the vid??

 

good write up, but next time use white lettering..........

Red is har to read...