2014+ Exhaust Systems & Mufflers

chuckl1218 · November 18, 2015

First, the GMPP Borla muffler for the 2014/2015 GM trucks is a Touring, not a Sport version. (Conversely, Corsa uses a Sport and does not offer a Touring version)

Second, I don't know whether the muffler can be purchased separately because I have never found a part number list showing separate components from the "Exhaust System". There are different part numbers for split dual or side exit or 5.3L or 6.2L and cab/bed combination. But they mainly just use a different length front pipe for each system type and they just show the kit part number, not components in the installation instructions. Their phone number is included in the instructions if you want to contact them...

http://gmcaad.com/wp-content/uploads/Borla-Silverado-Dual-Side-Exit-Installation-Sheet.pdf

Edited November 18, 2015 by chuckl1218

volrus · November 18, 2015

Thanks, very helpfu!

Kerrslight · November 18, 2015

Finally got a cool morning here in Houston. Trucks run so much better when they've actually got cool air running through them. Call my crazy but throttle response felt better, overall power seemed improved, and my exhaust even sounded deeper. My last truck was like this too. Love it.

6D9 Matt · November 21, 2015

Has anyone had any luck finding a dual black tip that looks good behind the rear passager tire???

http://redtailperformance.com/

Mike1220 · November 23, 2015

Finally got a cool morning here in Houston. Trucks run so much better when they've actually got cool air running through them. Call my crazy but throttle response felt better, overall power seemed improved, and my exhaust even sounded deeper. My last truck was like this too. Love it.

winter is like bolting on some extra horsepower to the truck. I always know when its winter cause my MPGs go down, avg speed goes up, and I look for more empty roads

TheBigGrabowsky · November 23, 2015

You know, I'm a little irked with the exhaust systems on our trucks. GM really made it difficult to make a nice sounding system. It looks like our only options are the GM/Borla exhaust for $1300, but which is not really much louder than stock (so I hear) or a custom setup which will cause the truck to drone in V4 mode. That's lame.

Using a tuned flapper to phase cancel the V4 exhaust pulses was pretty ingenious for the stock setup, but once you change the back pressure the flapper will not "flap" at the proper resonance and will basically become a noise maker. Borla seems to be the only ones who figured out how to replicate the flapper on a less restrictive exhaust and unless your local exhaust guy is a fluids engineer, you're not likely going to find a better solution.

Anastazi Sarigiannis · November 24, 2015

You know, I'm a little irked with the exhaust systems on our trucks. GM really made it difficult to make a nice sounding system. It looks like our only options are the GM/Borla exhaust for $1300, but which is not really much louder than stock (so I hear) or a custom setup which will cause the truck to drone in V4 mode. That's lame.

Using a tuned flapper to phase cancel the V4 exhaust pulses was pretty ingenious for the stock setup, but once you change the back pressure the flapper will not "flap" at the proper resonance and will basically become a noise maker. Borla seems to be the only ones who figured out how to replicate the flapper on a less restrictive exhaust and unless your local exhaust guy is a fluids engineer, you're not likely going to find a better solution.

All Borla did was take the stock flapper and put it in FRONT of their muffler on their GMPP system. Anyone could do the same thing. Cut out the stock muffler, flapper and resonator, and mover the flapper up behind the 3rd cat, install a magnaflow or borla muffler after the flapper, and then a piece of pipe back where the rear resonator was and viola, same as Borla.

Kerrslight · November 24, 2015

All Borla did was take the stock flapper and put it in FRONT of their muffler on their GMPP system. Anyone could do the same thing. Cut out the stock muffler, flapper and resonator, and mover the flapper up behind the 3rd cat, install a magnaflow or borla muffler after the flapper, and then a piece of pipe back where the rear resonator was and viola, same as Borla.

Correct me if I'm wrong, but that would still take quite a bit away from the sound of the muffler

Anastazi Sarigiannis · November 24, 2015

Correct me if I'm wrong, but that would still take quite a bit away from the sound of the muffler

No, it should have negligible effect on the exhaust sound, and regardless, the proof is in the pudding. It's what Borla did. At low gas flow rates like idle and cruise in V4 mode, the flapper modulates the exhaust pulses, but one you tromp on the gas, the flapper opens fully, so it doesn't affect how the muffler works, as at that point it's doing nothing. That way you keep the nice exhaust note, but eliminate the V4 resonance.

Anyone, like yourself, who has modified the stock system and still has their flapper, could take that flapper and install it between the 3rd catalytic conver and their muffler and it should drastically reduce the V4 chopper noise.

Paying $1300 for an exhaust system from the dealer is crazy.

Here's the system:

And here's the adaptive valve (aka flapper). Borla also added a bypass to the setup, presumable for cold startup to alleviate any issues from the valve sticking in freezing temps until the exhaust warms up.

Edited November 24, 2015 by SIG551A1

TheBigGrabowsky · November 24, 2015

Borla uses airflow simulation software to design their exhausts. You are only speculating as to what the small bypass tube is doing. The only way to mimic the Borla correctly would be to use the exact same tube diameters, lengths, muffler type and size, etc.

If someone could measure the following on their Borla I will be the guinea pig:

1. Tubing size (including bypass)

2. Flapper size (stock 5.3 or 6.2 version? )

3. Muffler length, width and height.

CptMcSaug · November 24, 2015

Borla uses airflow simulation software to design their exhausts. You are only speculating as to what the small bypass tube is doing. The only way to mimic the Borla correctly would be to use the exact same tube diameters, lengths, muffler type and size, etc.

If someone could measure the following on their Borla I will be the guinea pig:

1. Tubing size (including bypass)

2. Flapper size (stock 5.3 or 6.2 version? )

3. Muffler length, width and height.

Or buy a Diablo and tune out the V4 mode and then buy a 400 exhaust system. Boom saved you 600 bucks...

TheBigGrabowsky · November 24, 2015

I'm probably the minority here, but I want to retain the V4 function. I'm averaging 19.5 mpg right now and most of that is due to keeping it in V4 as often as possible.