I am reposting this from the other GX forum.
Background:
My GX460 serves as the daily driver, overlander, and future baby hauler, so noticeable drone was not an
option. I looked at all the available bolt-on options (listed below) and decided none of them quite fit
what I was looking for, so I purchased two mufflers (one absorptive and one reactive design). My
thought process being: I can swap the factory muffler and resonator out with the new mufflers. If the
setup is too loud or drones, I can add the factory resonator back, giving me 4 different exhaust
combinations to choose from.
If you are unfamiliar with muffler design, this is a good guide to review: Understanding Muffler Design
and Sound Absorption Strategies - Dragzine
GX460 Bolt-on options:
-Rev9 cat-back - no mention of 100% 304 stainless steel construction. No details on muffler
design. Straight through, absorptive muffler.
-MagnaFlow cat-back - no mention of 100% 304 stainless steel construction. Absorptive muffler
with a very similar design to the Borla ProXS.
-aFe Vulcan cat-back - 304 stainless steel construction. Described as a “turbo” muffler usually
meaning S-shaped exhaust path, so not a straight through design, but it should flow fine.
-Carven dump-exit - no mention of 100% 304 stainless steel construction. Muffler looks like a
Carven “TR”. The Carven website describes the TR muffler as “fiberglass packed” aka absorptive.
The inside looks nearly identical to standard resonator or bullet muffler. This is a simple, straight
through design and should be louder than the Magnaflow or aFe, possibly with more drone.
No Muffler:
I figured why not? The exhaust note was surprisingly nice, but had serious drone, slight cabin vibration,
and sounded like someone stole my cats on start up. I was tired of it after a day.
Borla ProXS:
This was the first muffler I tried after removing the factory one. I picked this absorptive muffler for its
mild exhaust note, low price, 304 stainless casing, and ease of installation. The exhaust note is mellow
and deep. I first tried the Borla without the resonator. It was too bassy in the car and did resonate to the
point of being slightly annoying on the highway, but it sounds great. After adding the resonator back on,
the deep V8 rumble was still there, but the volume was cut in half. Borla plus factory resonator sounds
like a 392 Hemi stock exhaust, volume wise. Very deep tone, zero rasp, truck-like note. If your engine is
warm, your neighbors may not even notice you have an exhaust until you go about 1/2 throttle. The
downside to this setup is the absence of high rpm notes and very slight drone (but totally manageable).
The lack of higher pitched notes is due to muffler design, the fiber packing cancels out high frequencies
really well.
Pros - universal design, reversible, deep and mellow tone, no rasp, low price, classic V8 sound, won’t piss
off the neighbors.
Cons - 304 stainless case is very thin and not as high quality as Corsa, very slight drone under light
acceleration and some highway cruising speeds, not as corrosion resistant, limited high frequency notes.
Corsa PRO Series:
My final exhaust setup on my CTS-V included Corsa Sport mufflers. I loved this setup, so I’m honestly a
little biased, but I’m doing my best to be objective. I chose this reactive muffler for its build quality, “no
drone” technology, unique sound, and tone range. The quality of the 304 stainless is impressive, it looks
like a Yeti tumbler and the steel is thick. Every Corsa Sport, Extreme, and Pro muffler is chambered with
zero fiber packing. This design has its pros and cons, allowing some rasp because fiber packing isn’t
there to tone it down, but the exhaust note is present from idle to redline and has a more exotic sound.
On to my initial impressions, first start up after welding the Pro Series muffler in was “this is too loud for
a Lexus SUV.” Corsa with no resonator is a little raspy, aggressive, and would upset your neighbors on
cold start. The following day, I went back to the muffler shop to reweld the factory resonator. After
adding it back, I knew I found the sound I was looking for. The resonator does a great job of calming the
Corsa muffler down. On cold start, the exhaust barks a little, especially in cold weather. It quickly
mellows out to a mild rumble at idle. It’s not as deep as the Borla at idle due to the chambered design,
but it has more burble and personality without being obnoxious. The Corsa has a strange ability to go
from near silent to loud depending on where your foot is on the gas pedal. You can valet park without
drawing any attention whatsoever or be the annoying person in the parking garage if that’s your thing.
The lack of drone is what sold me though. Driving around town at a normal pace or in traffic is barely
louder than stock. The only hint of drone occurs on mild inclines or at 80 mph plus and most passengers
won’t notice it. I don’t even know if I’d call it drone, it’s just barely audible noise. My wife recently took the
GX from Houston to Austin with 3 friends and none of them knew the exhaust was modified.
Pros - reversible design, build quality, corrosion resistance, range of exhaust note, lack of cabin drone,
wife approved.
Cons - expensive, can be raspy without a resonator, not as deep as the Borla, louder in cold weather.
Conclusion:
The factory muffler is chambered and well-engineered. While it’s not a straight-through design, it looks
to flow reasonably well and should last the life of the vehicle. Will an aftermarket exhaust increase
horsepower on the GX460? Maybe a few horsepower, but nothing noticeable or worth worrying about.
We can’t tune these engines to begin with. Both the Borla and Corsa cases are smaller in every
dimension compared to the factory muffler, making them easy to install and offering better ground
clearance. The existing full cat-back offerings look fine, I would go aFe or Magnaflow if you want all new
plumbing and a bolt-on solution. If you want to save a dime or want something different, Borla and
Corsa make great options and muffler shops will charge roughly $80 to install.
*In the video, you may hear a slight howl at high rpm with the Corsa. This was due to an incomplete
weld in the factory piping (caused by the muffler shop welder, not Corsa) and has since been addressed.
Use a subwoofer for a better idea of the bass note differences between the Borla and Corsa.
Background:
My GX460 serves as the daily driver, overlander, and future baby hauler, so noticeable drone was not an
option. I looked at all the available bolt-on options (listed below) and decided none of them quite fit
what I was looking for, so I purchased two mufflers (one absorptive and one reactive design). My
thought process being: I can swap the factory muffler and resonator out with the new mufflers. If the
setup is too loud or drones, I can add the factory resonator back, giving me 4 different exhaust
combinations to choose from.
If you are unfamiliar with muffler design, this is a good guide to review: Understanding Muffler Design
and Sound Absorption Strategies - Dragzine
GX460 Bolt-on options:
-Rev9 cat-back - no mention of 100% 304 stainless steel construction. No details on muffler
design. Straight through, absorptive muffler.
-MagnaFlow cat-back - no mention of 100% 304 stainless steel construction. Absorptive muffler
with a very similar design to the Borla ProXS.
-aFe Vulcan cat-back - 304 stainless steel construction. Described as a “turbo” muffler usually
meaning S-shaped exhaust path, so not a straight through design, but it should flow fine.
-Carven dump-exit - no mention of 100% 304 stainless steel construction. Muffler looks like a
Carven “TR”. The Carven website describes the TR muffler as “fiberglass packed” aka absorptive.
The inside looks nearly identical to standard resonator or bullet muffler. This is a simple, straight
through design and should be louder than the Magnaflow or aFe, possibly with more drone.
No Muffler:
I figured why not? The exhaust note was surprisingly nice, but had serious drone, slight cabin vibration,
and sounded like someone stole my cats on start up. I was tired of it after a day.
Borla ProXS:
This was the first muffler I tried after removing the factory one. I picked this absorptive muffler for its
mild exhaust note, low price, 304 stainless casing, and ease of installation. The exhaust note is mellow
and deep. I first tried the Borla without the resonator. It was too bassy in the car and did resonate to the
point of being slightly annoying on the highway, but it sounds great. After adding the resonator back on,
the deep V8 rumble was still there, but the volume was cut in half. Borla plus factory resonator sounds
like a 392 Hemi stock exhaust, volume wise. Very deep tone, zero rasp, truck-like note. If your engine is
warm, your neighbors may not even notice you have an exhaust until you go about 1/2 throttle. The
downside to this setup is the absence of high rpm notes and very slight drone (but totally manageable).
The lack of higher pitched notes is due to muffler design, the fiber packing cancels out high frequencies
really well.
Pros - universal design, reversible, deep and mellow tone, no rasp, low price, classic V8 sound, won’t piss
off the neighbors.
Cons - 304 stainless case is very thin and not as high quality as Corsa, very slight drone under light
acceleration and some highway cruising speeds, not as corrosion resistant, limited high frequency notes.
Corsa PRO Series:
My final exhaust setup on my CTS-V included Corsa Sport mufflers. I loved this setup, so I’m honestly a
little biased, but I’m doing my best to be objective. I chose this reactive muffler for its build quality, “no
drone” technology, unique sound, and tone range. The quality of the 304 stainless is impressive, it looks
like a Yeti tumbler and the steel is thick. Every Corsa Sport, Extreme, and Pro muffler is chambered with
zero fiber packing. This design has its pros and cons, allowing some rasp because fiber packing isn’t
there to tone it down, but the exhaust note is present from idle to redline and has a more exotic sound.
On to my initial impressions, first start up after welding the Pro Series muffler in was “this is too loud for
a Lexus SUV.” Corsa with no resonator is a little raspy, aggressive, and would upset your neighbors on
cold start. The following day, I went back to the muffler shop to reweld the factory resonator. After
adding it back, I knew I found the sound I was looking for. The resonator does a great job of calming the
Corsa muffler down. On cold start, the exhaust barks a little, especially in cold weather. It quickly
mellows out to a mild rumble at idle. It’s not as deep as the Borla at idle due to the chambered design,
but it has more burble and personality without being obnoxious. The Corsa has a strange ability to go
from near silent to loud depending on where your foot is on the gas pedal. You can valet park without
drawing any attention whatsoever or be the annoying person in the parking garage if that’s your thing.
The lack of drone is what sold me though. Driving around town at a normal pace or in traffic is barely
louder than stock. The only hint of drone occurs on mild inclines or at 80 mph plus and most passengers
won’t notice it. I don’t even know if I’d call it drone, it’s just barely audible noise. My wife recently took the
GX from Houston to Austin with 3 friends and none of them knew the exhaust was modified.
Pros - reversible design, build quality, corrosion resistance, range of exhaust note, lack of cabin drone,
wife approved.
Cons - expensive, can be raspy without a resonator, not as deep as the Borla, louder in cold weather.
Conclusion:
The factory muffler is chambered and well-engineered. While it’s not a straight-through design, it looks
to flow reasonably well and should last the life of the vehicle. Will an aftermarket exhaust increase
horsepower on the GX460? Maybe a few horsepower, but nothing noticeable or worth worrying about.
We can’t tune these engines to begin with. Both the Borla and Corsa cases are smaller in every
dimension compared to the factory muffler, making them easy to install and offering better ground
clearance. The existing full cat-back offerings look fine, I would go aFe or Magnaflow if you want all new
plumbing and a bolt-on solution. If you want to save a dime or want something different, Borla and
Corsa make great options and muffler shops will charge roughly $80 to install.
*In the video, you may hear a slight howl at high rpm with the Corsa. This was due to an incomplete
weld in the factory piping (caused by the muffler shop welder, not Corsa) and has since been addressed.
Use a subwoofer for a better idea of the bass note differences between the Borla and Corsa.
), but I'll save the throaty, louder volumes for more of a sporty street vehicle.
