2015 5.3 3RD CAT DELETE HELP

joshc64311 · July 17, 2015

I have deleted the muffler, flapper valve and resonator and replaced them with a flow master 40 delta flow. so what are the pros/cons of deleting the 3rd cat, is there a decreas in mpg low end tq/hp, will it get louder.

Edited July 17, 2015 by joshc64311

lam0205 · July 17, 2015

I deleted the third cat on my 14 5.3l with a 70 series muffler. As far as difference in power/torque I'm not certain as I did it all at once, but definitely didn't hurt it.

Cohen · July 17, 2015

Been looking at the different exhaust options, would much rather just go this route than dropping 1k on an exhaust. Do either of you get a drone with this?

TJay74 · July 18, 2015

Wont hurt a thing, it is not monitored by the ECM and was only added to make the GM trucks meet the stricter California emission requirements. They did the same thing from the 2008 Pontiac G8 to the 2009 G8. We looked at the programming and there was no change, other than the 2009 made 6hp less than the 2008 due to the 3rd cat.

joshc64311 · July 18, 2015

Been looking at the different exhaust options, would much rather just go this route than dropping 1k on an exhaust. Do either of you get a drone with this?

to be honest not really, you will here a slight difference in sound when it switches from V8-V4 at low rpm like under 2000rpm. I don't think its all that bad tho, people blow the helicopter sound way out of proportion

joshc64311 · July 18, 2015

Wont hurt a thing, it is not monitored by the ECM and was only added to make the GM trucks meet the stricter California emission requirements. They did the same thing from the 2008 Pontiac G8 to the 2009 G8. We looked at the programming and there was no change, other than the 2009 made 6hp less than the 2008 due to the 3rd cat.

did you lose any mpg?

lam0205 · July 18, 2015

I had a 70 series flowmaster which was not much louder than stock it just made it sound like a truck. I did not think the drone was bad at all... But you can hear it!