C4 Drone from Muffler Delete
Thread Starter
1st Gear
Joined: Jan 2024
Posts: 1
Likes: 0
C4 Drone from Muffler Delete
Hey! New 1995 c4 owner here. Recently bought a shiny new c4 a few weeks ago and have encountered an annoying issue I'm hoping yall can help me with. When I bought it, and the little test drives I did, it sounded great and I did NOT realize it had a muffler delete exhaust system. I thought it was weird, it came with mufflers in the trunk but when I took it somewhere for a tune up I found out the thing had no mufflers installed. I asked some local shops who told me they'd charge 300-320 to install the two magnflow mufflers I already have (the car included in the trunk when I bought it). The sound is fine for 10-20 minute drives but anything over gives a massive headache.
Here's what I want to know:
- Will installing Magnaflow mufflers substantially reduce the drone/noise as compared to its current muffler delete?
- Is the drone/noise issue inside the cabin due more to the exhaust or insulation? Would taking the seats and carpet out and putting insulation mats there get rid of the overpowering noise?
- ANY AND ALL RECOMMENDATIONS, Im in the MD/VA area
Thank you
Here's what I want to know:
- Will installing Magnaflow mufflers substantially reduce the drone/noise as compared to its current muffler delete?
- Is the drone/noise issue inside the cabin due more to the exhaust or insulation? Would taking the seats and carpet out and putting insulation mats there get rid of the overpowering noise?
- ANY AND ALL RECOMMENDATIONS, Im in the MD/VA area
Thank you
Heel & Toe
Joined: Sep 2021
Posts: 19
Likes: 5
Drone
Hello had the same condition after I installed a complete BB stainless system. Knew I would get some drone but yes after an hour what a headache, so I installed 2 layers of Boom Mat under the rear carpet. Very little improvement that glass hatch is an echo chamber.
Put it on the forum for advise and because it has quad tips a member recommended using a plumbers pipe plug on the inboard ports. I went with the standard 2.5" system instant relief, cannot tell any performance let down.
Cheap and effective hope this helps.
Put it on the forum for advise and because it has quad tips a member recommended using a plumbers pipe plug on the inboard ports. I went with the standard 2.5" system instant relief, cannot tell any performance let down.
Cheap and effective hope this helps.
Melting Slicks
Joined: May 2014
Posts: 2,846
Likes: 578
From: New Port Richey FL
Putting them back on will probably reduce the drone just from the added mass the exhaust get the residence vibration though the car.
If interested if it doesn't fix it to the point you're happy I have a low mileage Factory exhaust that was removed with 1st oil change in 95. I bought it about 10 years ago and I have had sitting in the garage or trailer since and before that it was in the rafters of a shop.
If interested just send me a PM and we can work it out
If interested if it doesn't fix it to the point you're happy I have a low mileage Factory exhaust that was removed with 1st oil change in 95. I bought it about 10 years ago and I have had sitting in the garage or trailer since and before that it was in the rafters of a shop.
If interested just send me a PM and we can work it out
Last edited by s carter; Jan 13, 2024 at 06:04 PM.
Pro
Joined: Sep 2019
Posts: 716
Likes: 135
From: Buchanan, Michigan
fyi, the oem catback exhaust on all 92-96 corvettes is good to 400-415 rwhp. the big restriction is the stock manifolds and catalytic converters. any perceived gain in power on a stock lt1 is strictly placebo effect. you spent money and your brain refuses to believe it did not make the car faster. put the stock exhaust back on. i used it with long tube headers on my c4 and it totally changes the sound, but zero drone. gm used the same catback on the zr1 that was rated at 405, then 425 horsepower. sure you can make more power with a better system, but for a basically stock street lt1 it is not worth the drone, headache (literally), and potential ticket for loud exhaust.
put some good headers on it with stock 92-96 catback. you will like it.
put some good headers on it with stock 92-96 catback. you will like it.
Instructor
Joined: Jan 2022
Posts: 236
Likes: 102
fyi, the oem catback exhaust on all 92-96 corvettes is good to 400-415 rwhp. the big restriction is the stock manifolds and catalytic converters. any perceived gain in power on a stock lt1 is strictly placebo effect. you spent money and your brain refuses to believe it did not make the car faster. put the stock exhaust back on. i used it with long tube headers on my c4 and it totally changes the sound, but zero drone. gm used the same catback on the zr1 that was rated at 405, then 425 horsepower. sure you can make more power with a better system, but for a basically stock street lt1 it is not worth the drone, headache (literally), and potential ticket for loud exhaust.
put some good headers on it with stock 92-96 catback. you will like it.
put some good headers on it with stock 92-96 catback. you will like it.
Also, how does it change the sound? And what do you consider "good" headers? Did you have to re-tune after you installed the headers?
Last edited by Rogue One; Jan 16, 2024 at 09:28 AM.
Advanced
Joined: Oct 2020
Posts: 59
Likes: 2
From: Azusa, CA
Hello had the same condition after I installed a complete BB stainless system. Knew I would get some drone but yes after an hour what a headache, so I installed 2 layers of Boom Mat under the rear carpet. Very little improvement that glass hatch is an echo chamber.
Put it on the forum for advise and because it has quad tips a member recommended using a plumbers pipe plug on the inboard ports. I went with the standard 2.5" system instant relief, cannot tell any performance let down.
Cheap and effective hope this helps.
Put it on the forum for advise and because it has quad tips a member recommended using a plumbers pipe plug on the inboard ports. I went with the standard 2.5" system instant relief, cannot tell any performance let down.
Cheap and effective hope this helps.
Last edited by Kojowatu; Jan 19, 2024 at 03:36 PM. Reason: To contact advisor
Drifting
Joined: Feb 2017
Posts: 1,271
Likes: 398
From: Tacoma WA
2024 C4 of the Year Finalist - Unmodified
I have stainless works headers with no cats into the remaining stock exhaust on my 95. I like the sound and there is no drone. The headers have bungs for the O2 sensors in the collectors so the computer functions normally since the readings from the O2 sensors are pre cats. Of course you will get more unburned fuel smell since the cats are no longer there to clean it up.
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Safety Car
Joined: Jun 2010
Posts: 4,564
Likes: 1,675
It has been suggested before. Most people are just going to go ahead and do the exhaust as they like the look anyways.
All the power to be gained is in the headers. I would absolutely use cats as the stench is awful not just for you, but the poor people behind you.
In a race car, I’m running headers with no cats and a stock exhaust. In testing, I think I lost 5 Hp using the factory cat back. And that is on a modified engine. So I’m not worried about it.
Heel & Toe
Joined: Sep 2021
Posts: 19
Likes: 5
The Billy Boat system has dual tips on each side, member recommended installing a pipe plug on inside exhaust. It's only 2 galvanized washers on each side side of a threaded bolt with neoprene washers. Just get the right size goes in easy , ratchet it tight, heat does not affect the thick washers.
Bought them online, I just want cruising quiet, again don't notice any performance drop off.
Let me know.
Bought them online, I just want cruising quiet, again don't notice any performance drop off.
Let me know.
Drifting
Joined: Aug 2009
Posts: 1,959
Likes: 241
keep the mufflers, eliminate the center resonator. It livens up the sound and is more aggressive, no droning.
Instructor
Joined: Jan 2022
Posts: 236
Likes: 102
That said, I was really just asking the question. It wasn’t my intention to remove the cats due to the smell as Chump pointed out.I like the look of the stock muffler and tips, so they will stay. Headers and an X-Pipe sound about right.
Le Mans Master
Joined: Jul 2000
Posts: 7,631
Likes: 322
From: Greenville SC
Manual or auto? With a ZF you can adjust to reduce the drone in most cases.
I had eliminators on my 95 first, drone, so I added an X pipe in place of resonator, was a really good sound, raspy with a decent sound level, unlike the quiet stock mufflers. (Foxbody Flowmaster 5.0 like sound)
It did have some pops and bangs on downshifts from higher RPM. This worked great on a stock car, but once I did heads and cam I added Magnaflows, but way to loud, then replaced with Corsa, still too loud but helped with drone, then added a center X resonator, great sound now and no drone.
I had eliminators on my 95 first, drone, so I added an X pipe in place of resonator, was a really good sound, raspy with a decent sound level, unlike the quiet stock mufflers. (Foxbody Flowmaster 5.0 like sound)
It did have some pops and bangs on downshifts from higher RPM. This worked great on a stock car, but once I did heads and cam I added Magnaflows, but way to loud, then replaced with Corsa, still too loud but helped with drone, then added a center X resonator, great sound now and no drone.
Race Director
Joined: Nov 2003
Posts: 12,220
Likes: 446
From: Overland Park Kansas
2020 Corvette of the Year Finalist (appearance mods)
C4 of Year Winner (appearance mods) 2019
Since you wanted any and all suggestions, Google Heimholz Resonator....also do it on Youtube. It's really tough to find a place for the J-pipes (which eliminate drone via 1/4 wave cancellation) but some have done it.
Using traditional mufflers eliminates sound pretty much across the frequency ranges...including the harmonic frequency where exhaust sound causes "drone"***.
Of course Corsa integrates this in their mufflers as POSSIBLY Borla Cratemufflers do. (At least Borla claims some anti-drone tech in that model).
***NOTE: Technically, drone is a harmonic "dissonance" where the frequency actually reverberates. Many call it the native cabin frequency where sound is loudest in the exhaust spectrum. (I call the later drone too.)
Using traditional mufflers eliminates sound pretty much across the frequency ranges...including the harmonic frequency where exhaust sound causes "drone"***.
Of course Corsa integrates this in their mufflers as POSSIBLY Borla Cratemufflers do. (At least Borla claims some anti-drone tech in that model).
***NOTE: Technically, drone is a harmonic "dissonance" where the frequency actually reverberates. Many call it the native cabin frequency where sound is loudest in the exhaust spectrum. (I call the later drone too.)
Drifting
Joined: Mar 2006
Posts: 1,263
Likes: 188
From: Wabasha Mn
Hello had the same condition after I installed a complete BB stainless system. Knew I would get some drone but yes after an hour what a headache, so I installed 2 layers of Boom Mat under the rear carpet. Very little improvement that glass hatch is an echo chamber.
Put it on the forum for advise and because it has quad tips a member recommended using a plumbers pipe plug on the inboard ports. I went with the standard 2.5" system instant relief, cannot tell any performance let down.
Cheap and effective hope this helps.
Put it on the forum for advise and because it has quad tips a member recommended using a plumbers pipe plug on the inboard ports. I went with the standard 2.5" system instant relief, cannot tell any performance let down.
Cheap and effective hope this helps.
Melting Slicks
Joined: Oct 2012
Posts: 2,153
Likes: 269
From: Dunedin NZ.
Since you wanted any and all suggestions, Google Heimholz Resonator....also do it on Youtube. It's really tough to find a place for the J-pipes (which eliminate drone via 1/4 wave cancellation) but some have done it.
Using traditional mufflers eliminates sound pretty much across the frequency ranges...including the harmonic frequency where exhaust sound causes "drone"***.
Of course Corsa integrates this in their mufflers as POSSIBLY Borla Cratemufflers do. (At least Borla claims some anti-drone tech in that model).
***NOTE: Technically, drone is a harmonic "dissonance" where the frequency actually reverberates. Many call it the native cabin frequency where sound is loudest in the exhaust spectrum. (I call the later drone too.)
Using traditional mufflers eliminates sound pretty much across the frequency ranges...including the harmonic frequency where exhaust sound causes "drone"***.
Of course Corsa integrates this in their mufflers as POSSIBLY Borla Cratemufflers do. (At least Borla claims some anti-drone tech in that model).
***NOTE: Technically, drone is a harmonic "dissonance" where the frequency actually reverberates. Many call it the native cabin frequency where sound is loudest in the exhaust spectrum. (I call the later drone too.)
I have the older Billy Boat system which does drone so I made reducers to to fit in the outer exhaust tips to reduce the size of the outlet by 50% - this got rid of the drone and I don't notice any reduction in performance.
Drifting
Joined: Apr 2000
Posts: 1,390
Likes: 35
From: INDIANA
Unless your state has a mandatory inspection, there is no one enforcing the federal requirement (at least at this time, who knows with the way things are going). I wouldn't worry about the cats.
Melting Slicks
Joined: Oct 2012
Posts: 2,153
Likes: 269
From: Dunedin NZ.
https://images.app.goo.gl/n6wXHNhjKnNmQLxb9
Have a look at this site, the info is there re helmholtz resonators
Have a look at this site, the info is there re helmholtz resonators
Burning Brakes
Joined: Aug 2023
Posts: 1,093
Likes: 35
From: San Diego
Corsas cat back, flowmasters cat back on my 93 made zero drone. I had Long Tube headers and a 396LT1.
Current set up is OEM cat back with the long tubes. Sounds perfect, zero drone.
No drone is what you want for sanity. Long tubes gives some real good power back to any small block Chevy.
Current set up is OEM cat back with the long tubes. Sounds perfect, zero drone.
No drone is what you want for sanity. Long tubes gives some real good power back to any small block Chevy.