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2020 Chevy RST 6.2L Muffler/Flappers deleted and my experience


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Yes I know a bunch have done this and I read most post about doing it.  I am going to go to a Borla S-Type system 140779BC and decided in the interim to cut off the muffler and both flappers and had a 3.5" pipe welded in place.  Here are my thoughts after driving it around town and open road for a day.  Don't do it lol!  Upon initial startup at the muffler shop I was impressed and love the deep throaty rumble, even cold start the next day was great but that's where it ends.  The drone inside the cab is way too loud and yes when DFM kicks in you get a really loud helicopter sound that comes and goes at random.  Put it in Manual mode and not helicopter sound and a little quieter.  The drone is even louder under mild acceleration or when the motor is under load going up a hill even on open road.  The interesting part is the throttle response feels sluggish compared to before the mod.  When you get on it it moves really good but still feels a little like it lost a few hp.  Maybe that's me but that's the way it feels.  The sound under wide open throttle is pretty good, and as my neighbor put it...I sound like a teenager coming down the road lol!  He did say it was LOUD!  He was several hundred yards away outside his house as I left and accelerated hard down the road.  In town driving the drone and sluggishness is very annoying.  Definitely leave it in manual mode in town.  I did a few hard downshifts and never experienced any popping sounds from deceleration.  If you get on it hard for a few seconds then let off, be prepared to have it screaming at you while waiting for the transmission to finally upshift  and rpms drop...and everyone starting at you.  It also highlighted what our motors do under low speed.  While on some back roads I was taking it real easy around 30 mph at a steady speed and ever so often the motor would blurp the rpms up then right back down but never shifted.  It did this more than once as if it was the computer adjusting for fuel/air and who knows what else but still very weird.  I have thought I noticed it do it before with muffler/flappers on but this was confirmation it does do it sometimes.  In summary, I would not recommend this mod without at least leaving the flappers on as I read in one other post or just swap the muffler.  I'm now pushing up my timeline for the Borla or going back to the shop and have them add at least an aftermarket muffler back on.

 

Anyone have anything else to add or similar experience please share.

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Yea, straight pipe without some sort of resonator or the flapper is rough.  Same with just welding in a small muffler like a Flowmaster or Magnaflow.  Most of the ones they offer are small bodied mufflers that don't offer much in the realm of resonance and drone absorption.  

 

Corsa for example uses almost a factory sized muffler.  I'm on my second system from them, zero drone whatsoever.  Its im my opinion the closest to a Camaro/Corvette dual mode in terms of sound quality when cruising, acceleration and WOT.  

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@newdude I ran the Corsa system on my old 2004 Chevy Silverado 5.3 since it was almost new until I traded it on this truck and loved it.  Quiet while driving but nice startup sound and when accelerating.  I almost wanted more sound out of it but anyone I passed said it was pretty loud under WOT.  

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Corsa is the best sounding system I have heard on these trucks in my opinion. I love mine and wouldn’t trade it for anything else. It is whisper quiet when driving but step on the gas and it wakes the GODS up!!😂😂

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On 7/30/2021 at 12:56 PM, bbmxta said:

@newdude I ran the Corsa system on my old 2004 Chevy Silverado 5.3 since it was almost new until I traded it on this truck and loved it.  Quiet while driving but nice startup sound and when accelerating.  I almost wanted more sound out of it but anyone I passed said it was pretty loud under WOT.  

I had the Corsa touring on my 2003 Sierra Denali 6.0L and next to having a true dual system, I was happy with the sound of start-up and acceleration also. The Corsa tips were a nice compliment too.

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On 7/30/2021 at 10:08 AM, newdude said:

Yea, straight pipe without some sort of resonator or the flapper is rough.  Same with just welding in a small muffler like a Flowmaster or Magnaflow.  Most of the ones they offer are small bodied mufflers that don't offer much in the realm of resonance and drone absorption.  

 

Corsa for example uses almost a factory sized muffler.  I'm on my second system from them, zero drone whatsoever.  Its im my opinion the closest to a Camaro/Corvette dual mode in terms of sound quality when cruising, acceleration and WOT.  


When you say closest to a Camaro dual mode, is that when the bypass is open?  I have a ‘17 SS with the dual mode exhaust and I just pulled the fuse so it stays open.  I ask because it sounds great on my Camaro but would be too much on a truck for my personal taste.  Thanks in advance for your thoughts!  Looking for something with a little more deep growl than stock but not as loud as my Camaro.

 

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I must have the mentality of a teenager 😀. I did the muffler delete and flapper removal and love it. It makes me smile every time I start the truck or get on the gas pedal. I have the 5.3, so maybe that makes a difference? So, definitely not an apples to apples comparison.

 

The truck is VERY loud and cold start up is crazy loud. The droning in the truck is there, but not too annoying to me. I've had a lot of people in the truck on long drives and no one has complained to me. I see/feel no change in performance.

 

Having said that, I can understand people not liking this mod and most people should just do the muffler delete and keep the flapper valve or just change the muffler.

 

I'm not sure I understand spending $1K plus for a new exhaust system on a non performance vehicle, but again, to each his own.

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1 hour ago, RPaul said:

Serious question as I’m debating the whole borla system vs a borla muffler and cutting flapper etc.

 

why would the entire cat back be noticably different?

I know there's likely some tuning done in the piping itself but I would bet that there's not a ton of difference

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Today the auto makers are trying to get every last ounce of power and efficiency out of their vehicles.  This does get tempered slightly by cost of materials and needing sound dampening but the pipes and systems themselves are NOT an issue.  Gone are the days of aluminized, narrow, crimp bent tubing with brick style cats and poor flowing mufflers.

 

Cut the factory muffler and flappers off, get something better flowing, and what little bit of performance improvement there is will be done for cheap.

 

Paying $600+ for an exhaust system that is 0.25" wider and marginally better flowing than the factory one is silly.  $1000 plus for a (maybe higher) grade of stainless steel is ridiculous.

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