The $1.00 "Cat-Back" Mod

[GTPprix]

I will preface this with I have only done this on my Yukon Denali, the rest of the trucks have the same setup but YMMV.

I am one of a few (at least two! ) people who have a chirp/squeak when the Exhaust Valve just aft of the main muffler moves. Its incredibly annoying and easily repeatable IE in 4 Cylinder Mode tip in to go back to V8 Mode and move the valve.

The parts catalog calls out not one but two different exhausts for this truck (probably one for the AVF trucks) so while I figure that out I figured I'd just hold the valve open. This remedied the squeak as I knew it would but it also added a great growl to the truck as well; much like the 2014 and previous had.

I'm also seeing a slight uptick in gas mileage at a time when it should go down due to colder weather. I have yet to hear any really bad drone at all in fact with my intake I havent really heard any YET.

The cool thing about this is it literally costs a $1.00 in parts LOL All you need is a 1/4x20 2" Bolt and a washer/lock washer. You rotate the valve counter clockwise till it stops and then put the bolt in under the spring holding the two halves still as shown.

 

[TheAgency]

Very cool! I've had my 15' SLT only for a few days (absolutely love it), but was a little taken aback by the lack of "growl". This looks like its easily reversed if things go south too.

I'll be doing this this weekend; keep us posted if you run into any problems or codes!

 

[GTPprix]

Code wise we are good, there isn't a sensor on the valve or any back pressure monitors. The valve is there for drone purposes in 4 Cylinder mode so the only downside would be drone at certain RPM's but like I said I haven't really had any yet. I also have an Air Raid intake which has a fantastic growl at medium-high throttle application

 

[Mad Maxx]

Just did this to see if it'll cure the buffeting sound in 4cyl mode.

The buffeting sound is def exhaust related IMO, so anything that can be done to try to eliminate it it worth a shot!

 

[Mr. Merk]

Just did this to see if it'll cure the buffeting sound in 4cyl mode.

The buffeting sound is def exhaust related IMO, so anything that can be done to try to eliminate it it worth a shot!

We tried it to no avail. I was convinced it was exhaust drone as well but it was not in our case.

 

[Mad Maxx]

We tried it to no avail. I was convinced it was exhaust drone as well but it was not in our case.

Seems like it helped a little bit on mine. The buffeting isn't as loud as it was / is at a different frequency now.

I'll leave it for a few more days and see if I still notice a difference.

Does seem to have a lil bit more low end now though. Nothing crazy, but noticeable.

 

[Rush]

Exhaust video clip?

 

[Mad Maxx]

Exhaust video clip?

Uploading now to Youtube.

Got a Cold Start / Rev & Hot Start / Rev.

I'll try to get a take off shot in the next few days.

---------- Post added at 03:05 PM ---------- Previous post was at 03:00 PM ----------

https://www.youtube.com/watch?v=G0ac4Od5M-0

https://www.youtube.com/watch?v=kMnEqXAtAE4

 

[Fifty]

Just did this. Sounds nice inside...a nice little rumble!

 

[nemloc]

Which sleek does it fix? Also, any other issues now that you've had it this long?


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