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New catted downpipe

10K views 19 replies 11 participants last post by  sqkid89 
#1 ·
Just received my catted downpipe from Trent @ TRS Fab in the mail last night. Its raining for the rest of the week around here, so I won't have any install pictures available for a bit. Just thought I'd share. Great build - super thick flanges, nice welds, good bends, nicely cleaned up insides (my flash does not do this piece justice). If you're looking to get new gaskets, part numbers appear to be 12609878 and 22759470. Some apparently have gotten by reusing their factory pieces, I prefer to use new and not worry about doing the job again.





 
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#8 ·
Well, a little more continuation (and instruction!):

Unless you've got a lift, you're going to want to get the front of the car up in the air. A pair of rhino ramps gave me just enough room to work underneath while still having access from the top (although I did have to stand on a milk crate to reach the front O2 connector).

Since we're working with electrical, as a safety precaution, you should typically undo the negative battery terminal. Chances of getting hurt are slim to none on this job, but you should always be on the safe side. Battery's in the trunk if you've not looked for it before.



Next, remove the heatshield. 3 10mm bolts and its off



Before taking the cat out, I *highly* recommend loosening up the O2 sensors. Its much easier with the pipe bolted in place than wrestling with it on the ground. Most part stores will rent you an oxygen sensor kit, or use your own tools. Pfadt calls for a 22mm wrench/socket here, my O2 sensor tool says 7/8"; either will do. The connectors are a HUGE pain. You need to pull the plastic lock tab out 2 clicks and then push realllllllly hard on it while pulling on the other end of the connector. Upstream connector is black and located near the engine towards the firewall. The rear one is gray and a pain to get at. I ended up snapping the retainer clip that held mine in place and pulling the connector apart from above. Its just way too tight from underneath. Here's it hiding.



Alright, here is what your next step should be, as it will be the most challenging from here out. Everything else is silly simple, but will require you to put it all back together if you cant get this step done. Unbolt (or at least loosen for now) the upper flange nuts. These are 15mm. The two closest to the driver fender are the easiest. The two next to the motor? Those are miserable. Be prepared to try a variety of sockets, extensions, wrenches, etc to get the clearance you need. You can see the top two in this photo:



Once you've gotten the top flange squared away, onto the easy stuff.

There's a bracket that holds the downpipe to the oil pan. Right near the lower flange. 2 13mm bolts, done. Then onto the lower flange. 2 15mm nuts. May want to hit these with some PB Blaster ahead of time, they get rusty. Looks to me like GM may not have used stainless hardware or flanges, as they are kinda rusty on my setup; everything else was pretty spotless.



...and this is where I must leave you guys for the moment. My tool collection was apparently lacking just enough that I could not get the upper flange bolts out. Fail. I've got a couple new sockets on the way, so I'll let you know what magical combination worked for me. If you were lucky enough to get everything apart, congrats. Reverse to install. Make sure to apply some anti-seize on the O2 sensor threads for easier removal in the future. Feel free to do the same on the other hardware as well. I bought new gaskets for my install, but GM appears to have used reuseable ones, so you may be lucky enough to not need new stuff. I didn't want to take the chance of a leak myself, $40 is not that much for peace of mind.
 
#9 ·
So I may have found the tool that I was lacking to get this job done. Quick test under the hood seems to have went well (not enough light out or time to get the job done), will hopefully conclude this install this weekend if mother nature gives me some sunshine to play with.

The missing link:

 
#12 · (Edited)
Success!

The ratchet made all the difference. This is what I got, but something similar should do the trick
http://www.sears.com/craftsman-3-8-...00944835000P?sLevel=0&redirectType=SKIP_LEVEL

Between the offset arm and the pivot head, I was able to get the clearance needed for those two silly nuts.

Quick recap:
upper downpipe flange nuts are 15mm, get yourself a deep socket. With a ratchet like shown above, only one will still require a bit of ingenuity. Thanks to a deep socket 1/2" drive 15mm, a 1/2" to 3/8" adapter, and my super ratchet, I got the clearance needed to get the last stubborn nut off.



Here's factory vs the catted TRS fab unit



If you're on the weight saving kick, the OE piece is about 13 1/2 lbs, TRS is about 5 3/4.

Also forgot to note one last fastener I missed on first try. This one is a cinch, just need a regular 13mm (1/2") socket or ratcheting wrech. You can see the socket in the photo for help



Now a couple installed pics



 
#16 ·
If you're not tuning, power won't change due to the PCM's ability to de-tune back to stock power levels. However, it does give the exhaust a slightly more aggressive sound. Before tuning, it would occasionally cause a CEL when coming off the highway, but not always. Around town driving never caused it to come on.
 
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