Performance exhaust... Which to buy?!

[cardude2000]

All:

Not to hijack the thread with another potential option, but I called Borla tech this afternoon and was informed they make a kit specifically for GM Performance Parts, 3" and 3.5" systems WITH a flapper valve, which eliminates ALL resonance. It's a single source agreement where the only option you have is to buy it from a GM dealer. The Borla rep went on to say that GM actually has the 'flapper' fabricated by someone else and they personally assemble the exhaust 'kit' for distribution to dealers. This entire thing was so far fetched to me that I actually called a second time, got another tech and the exact same answer. Finally, this "GM kit" is dual outlet, right side just like the regular Unit, but does not come with any tips, they must be ordered separately, and through GM (probably because they want the bowtie on the tip instead of "Borla." Unfortunately, I've been on GMPP's website and there isn't even a listing for any performance parts for a Tahoe. There is a listing for both a 3 and 3.5" for a Sliverado (5.3 and 6.2) respectively (see link below), but I see no evidence of a flapper valve. Can anyone verify this as true, and if so (and more importantly), provide the GM part number? Finally, in looking at photos of the factory flapper, it looks hugely restrictive. With the understanding that any catback kit is going to produce marginal performance gains, I'd wonder if the flapper might eliminate ANY power gain at all. I guess the big thing is whether or not the 'regular' Borla kit has resonance without the flapper. If the answer is no, I'll just get the 'regular' Borla kit. If it does resonate, this mystery GMPP kit might be work exploring. Thoughts appreciated.

Brian A.
2015 PPV
Silver Ice Metallic

http://www.chevrolet.com/performance/silverado-parts.html

Any idea if they are doing this for Yukon too?


Sent from my DynaTac8000 using Tapatalk

 

[Agent WD-40]

Now:

The big question is, does this kit truly have the flapper and is it really even needed? I'm still in a quandary as to why, if the 'regular' Borla kit has no resonance, anyone would spend several hundred dollars more for the GM kit (again, I see no evidence of a flapper but with such a small photo, it's nearly impossible to know)? Do cat backs that aren't from GM void the warranty?

Brian A.
2015 PPV
Silver Ice Metallic

I can say for a fact the GM accessories version of the Borla does have the flapper valve. The regular Borla version does not. I can also say for a fact that there is absolutely no perceivable change in tone when the car switches into V4 mode with the GM Borla exhaust on the 2015+ vehicles.

My dad has the GM Borla on his 2016 6.2 SUV. I have Corsa on my 2012 6.2 SUV. I was disappointed that I could my Yukon switch in and out of V4 mode after I installed the Corsa. It wasn't bad but it was enough to notice and it bothered me (there was also a very slight vibration I could feel through the floor when the truck kicked into V4 with my Corsa). I eventually had mine tuned and got rid of V4 mode (I also have a BB tune that kept V4 and made a big improvement in the annoyance of the switch).

For the reasons above I suggested the GM Accessory Borla to my father. I can verify it has none of the slight changes in tone or feel that mine does. Even windows down it doesn't sound weird kicking into V4 line mine did with the Corsa. The new trucks also are more aggressive in their use of V4 than the previous generation motors were so it would be more noticeable than it was in mine if there were a problem. I suspect this is also part of the reason the new vehicles have active noise cancelation - to mask the more aggressive use of use of V4.

I've never driven a non-GM Borla so I cannot comment from experience, but I would guess that GM didn't put the flapper in their exhaust because they wanted to make it more complicated or expensive. My thought is that the non-GM Borla will have a slight change in tone when it kicks into V4.

There are lots of folks over on the pickup truck forums that have the non-GM Borla and might be able to share a more direct comparison. I've seen plenty of guys on the truck forums complain of the more annoying use of V4 with their new trucks and aftermarket exhaust. Even people with Corsa have complained they can hear the truck switch in and out. Corsa did make a modification to their muffler to address that but I guess it isn't a perfect solution.

Bottom line, if I had a 2015+ the only exhaust I would do is the GM-Borla (or something custom that retains the flapper) unless I was getting V4 tuned out. Also, your PPV Tahoe likely doesn't have Active Noise Cancelation so it would probably be more noticeable in your SUV than others (active noise is standard on 6.2 and higher trim 5.3 if I'm not mistaken). I might be more sensitive to the V4 sound than most, but I wouldn't want to spend a lot of money And then be annoyed with the outcome.

 

[ZR WON]

I can say for a fact the GM accessories version of the Borla does have the flapper valve. The regular Borla version does not. I can also say for a fact that there is absolutely no perceivable change in tone when the car switches into V4 mode with the GM Borla exhaust on the 2015+ vehicles.

My dad has the GM Borla on his 2016 6.2 SUV. I have Corsa on my 2012 6.2 SUV. I was disappointed that I could my Yukon switch in and out of V4 mode after I installed the Corsa. It wasn't bad but it was enough to notice and it bothered me (there was also a very slight vibration I could feel through the floor when the truck kicked into V4 with my Corsa). I eventually had mine tuned and got rid of V4 mode (I also have a BB tune that kept V4 and made a big improvement in the annoyance of the switch).

For the reasons above I suggested the GM Accessory Borla to my father. I can verify it has none of the slight changes in tone or feel that mine does. Even windows down it doesn't sound weird kicking into V4 line mine did with the Corsa. The new trucks also are more aggressive in their use of V4 than the previous generation motors were so it would be more noticeable than it was in mine if there were a problem. I suspect this is also part of the reason the new vehicles have active noise cancelation - to mask the more aggressive use of use of V4.

I've never driven a non-GM Borla so I cannot comment from experience, but I would guess that GM didn't put the flapper in their exhaust because they wanted to make it more complicated or expensive. My thought is that the non-GM Borla will have a slight change in tone when it kicks into V4.

There are lots of folks over on the pickup truck forums that have the non-GM Borla and might be able to share a more direct comparison. I've seen plenty of guys on the truck forums complain of the more annoying use of V4 with their new trucks and aftermarket exhaust. Even people with Corsa have complained they can hear the truck switch in and out. Corsa did make a modification to their muffler to address that but I guess it isn't a perfect solution.

Bottom line, if I had a 2015+ the only exhaust I would do is the GM-Borla (or something custom that retains the flapper) unless I was getting V4 tuned out. Also, your PPV Tahoe likely doesn't have Active Noise Cancelation so it would probably be more noticeable in your SUV than others (active noise is standard on 6.2 and higher trim 5.3 if I'm not mistaken). I might be more sensitive to the V4 sound than most, but I wouldn't want to spend a lot of money And then be annoyed with the outcome.

Eric:

THANK YOU for finally verifying the flapper to be in place. I guess the big question is, how does the Borla *sound* on your Fathers truck? I can certainly hear/feel my PPV go in to V4 mode but honestly the noise itself doesn't bother me, likely because the stock exhaust is so quiet. Not entirely sure that I would or wouldn't mind it with a louder stock exhaust, my bigger concern is resonance.

Brian A.
2015 PPV
Silver Ice Metallic

 

[Agent WD-40]

The sys

Eric:

THANK YOU for finally verifying the flapper to be in place. I guess the big question is, how does the Borla *sound* on your Fathers truck? I can certainly hear/feel my PPV go in to V4 mode but honestly the noise itself doesn't bother me, likely because the stock exhaust is so quiet. Not entirely sure that I would or wouldn't mind it with a louder stock exhaust, my bigger concern is resonance.

Brian A.
2015 PPV
Silver Ice Metallic

The system on his truck has absolutely no resonance. It has a deep mellow tone inside the cab and isn't too obtrusive. It sounds throaty on acceleration but pretty much completely fades away when cruising on the highway or around town. It is on the more mild side but really has a great tone. I don't think anybody would mistake it for stock though. It sounds louder than the stock 2015 Mustang GT exhaust does.

I should add that my dad is happy with the sound and was extremely pleased with the quality of the system.

The flapper valve will definitely help the V4 noise but it should help keep resonance down when cruising too. I was playing with a flapper on a 2015 6.2L pickup after cold start. The engine was at idle and if I manually turned the flapper open by hand you could definitely hear more growl coming from the tailpipe with it open. It normally stays more closed at low engine speed with less exhaust flow (like it was at idle or would be at cruise). The flapper will get pushed open (and let through more sound) when you stand on it and the exhaust is flowing faster. I'm sure you would have more volume at low engine speed without a flapper (or if you clamped it open).

The flapper is just a passive version of the active valves GM puts on the Corvette and Camaro. It keeps the sound down at low engine speeds/exhaust flow. It jut cannot be actively opened at like the sports cars do.

If you want a gauge of sound - it sounds like any other Borla Touring system. The video below is a GM Borla system as you can see the flapper valve just after the flex pipe in the pictures. I think it sounds deeper/fuller/better in person than the video demonstrates though.

These are pickups with GM Borla systems (based on the title) but sound similar.

This is an official Borla video. The system they show in the picture has a flapper on it so it very well could be the GM Borla version. None the less it sounds similar to what my dad has.

 

[Agent WD-40]

Eric:

THANK YOU for finally verifying the flapper to be in place. I guess the big question is, how does the Borla *sound* on your Fathers truck? I can certainly hear/feel my PPV go in to V4 mode but honestly the noise itself doesn't bother me, likely because the stock exhaust is so quiet. Not entirely sure that I would or wouldn't mind it with a louder stock exhaust, my bigger concern is resonance.

Brian A.
2015 PPV
Silver Ice Metallic

I should have mentioned this in the post above but if I had to pick an exhaust for a current gen SUV I would pick the GM Borla over the Corsa. I love my Corsa, and I love the fact it doesn't drone, but now that I've seen firsthand there is no drone with the GM Borla system I would pick it. Both sound great - I just prefer the deep, smooth sound of the Borla over harder/edgier, more exotic sound of Corsa.

 

[NORCAL SS]

if its 6.2 go magnaflow. 3.5"

 

[affliction4]

What is the stock pipe size for the 5.3?

 

[NORCAL SS]

Just get the 3" muffler swap I have in my site for the 5.3s. I've done and sold many it's fine plus my prices are cheaper then amazon summit or jegs

 

[affliction4]

Thanks....sorry i am new here where do i find your site?




nevermind i found it....

So is there any drone in the cab with this muffler....the Tahoe is my wifes daily driver but im just adding things here and there so i can have fun when i drive it.

 

[NORCAL SS]

The 5x8x24 is fine if you leave resonator in. If you decide you want one notch louder you can delete the flapper behind muffler