I recently installed some long tube headers (no cats) on my 5.3 2013 GMC Sierra. I had a Borla XR1 and a street tune before the installation. I have not had the truck retune because the guy who tuned it is no longer at the same shop and I have been on a mission looking for him. The truck sounds great at start up and idle but when I step on it seems to make a loud kind of backfiring sound and that goes away once I get to 3 gear or so. Would this because I have not had it retuned or could it be misfiring? Any help would be greatly appreciated. Thanks!

 

Did you removed the spark plugs before you did the install? If not, you very well could have cracked one or damaged a plug wire... it's easy to do.

 

I had them done at a muffler shop so I'm not sure. Maybe I should take it back to them..

 

Just my opinion, maybe have it re tuned. Could work out the bugs.

 

I put long tubes with no cats on my brother in laws 2010. And it drove fine for about a month other than check engine light on due to no cats before we had it tuned. I'd get it to a tuner to see what codes you have.

 

It's unlikely the tune would be off enough to cause a misfire just from some long tubes especially if it was street tuned before. Yes you must get it tuned and the sooner the better but a plug and/or plug wire is most likely the issue.

Off topic but I'm really surprised a muffler shop installed headers without cats... They can get crazy fined for that.

 

Does it have a hollow or packed muffler

 

I had the truck re tuned and it still makes the sound. I think it sounds that way because of the muffler or because its a 5.3. I been reading that others add a bullet in front of the muffler.

 

Take a listen to my 5.3 with catless headers here: https://www.youtube.com/watch?v=WT0FHvMouf4

Mine didn't make any popping noise pre-tune, post tune, or post supercharger. Always has sounded like the video, that is with a corsa sport dual rear exit.

 

Well i ordered me a oval Borla to replace the circle Brola i have now and hopefully that fixes my issue with it.