[ZLRob]

Some of the ideas and mods posted here are based off the original mega thread of the Jones X pipe retrofit. In a sense I am actually going to consider this a spin off thread from that one. Link to the original thread down below:

https://www.camaro6.com/forums/showthread.php?t=576096

Tons of people in this forum and who own one of these cars in SS or ZL1 variants know firsthand that once you start making any sort of exhaust system changes the potential for drone opens right up, and it almost doesn't matter what you do. Longtube headers, secondary cat deletes mid pipe changes (X pipe delete, resonator deletes), or even something as simple as replacing the suitcase muffler in place of something like your favorite brand mufflers. If you have drone it is going to be a very annoying problem on longer road trips or potentially even around town. This can drive someone mad if they deal with things like Tinnitus or just have very sensitive hearing like I do (both unfortunately). I have added things like a secondary combination muffler and J pipes on top of the standard mufflers that I already have in place and it all helps, but only by margins. Something further had to be done so I started digging into more unconventional methods once exhaust hardware changes were not enough alone. The obvious solution in my situation was to throw the stock suitcase back on and call it a day, but I didn't want to do that for several reasons.







What I am about to post is a compilation of changes and modifications I have made that I have tested and proven audibly to either combat drone and if collectively done all contribute to a larger whole and will lead to a more than less drone free cabin either at low RPM around town or while driving:

- Sound dampening mat

This is no surprise here. Anyone who has been in the game long enough knows that this can help, and in some cases kill drone if it's an issue. These cars are so thin on the sheetmetal, however, that it is not a guarantee that it will work entirely. The lack of acoustic dampening that the factory uses in favor of things like ANC is a band-aid at best. I do understand why they do it but nevertheless... Matting can help, that much is for sure. With so many brands of sound dampening mat on the market available I am not going to begin recommending to you what brand you should get and what you should stay away from. You will need to do your homework on this.

- Active noise cancelling delete (ANC):

This is one that talked about and has been established in the community, but is not necessarily known about in large part by either new members or even long time members because there are no specific threads regarding it, its just sort of sprinkled into random threads here and there for the most part from what I have found. I have already made a thread regarding this and hopefully this brings it a little more to light for those with droney exhaust systems. Link below.

https://www.camaro6.com/forums/showthread.php?t=619862

- NPP exhaust

Next up is the NPP modifications which is not necessarily needed but highly recommended to make the most out of the oddly configured OE exhaust setup values. With so many different combinations available I don't feel that I am in place to recommend to you what settings you should and should not run. As my setup may be and most likely is different than yours. To those already familiar with the setup and even those just jumping into the game here's a quick recap:

Under System>General tab once unlocked in HPTuners, description reads "Active Exhaust"



Mode 0 = Tour
Mode 1 = Sport
Mode 2 = Track
Mode 3 = Snow/ Ice (stealth)

Exhaust Rumble (initial start up bark) Enable tab
Value 0 = off
Value 1 = on

Close % and Open % are adjusted the same way, make your initial adjustments and clone them to the other tab in the same mode.

NPP valve open value = -1
NPP valves close value = 100

This will require HPTuners and a CCM/ FSCM unlock in order to utilize and modify. Cost should be somewhere around $200 if I remember correctly, but it is entirely worth it to have full control over what those valves are doing if you have a droney setup but still have NPP valve retained in place.

Feel free to discuss adjustments and the settings you run in the thread.

- Timing modifications

This section requires full access to your tune and will require tuning credits from HPTuners to modify. Just a quick and obvious FYI before I get into this.

There are several modifications you can make to the factory tune in order to shut the engine up even further while cruising. Some are meant to handle initial start up bark and deceleration crackling that the factory tunes have setup in a certain way to make it loud and "poppy" for lack of a better word. I personally find it really annoying and unnecessary, but some like that sort of stuff. Those involve modifying the "Cat lightoff" parameters found in the "exhaust" tab of older HPTuners versions. The "Minimum Spark base" table and "Cutoff, DFCO" section under the "spark" and "fuel" tab respectively handles the crackling portion for those who want that or don't during decel. We are not here, however to talk about crackling and there are other threads for that.

The primary modification that I want to discuss is one that involves the standard timing octane tables namely the high octane base table which handles all of your timing when running 93/ ethanol blend/ E85. More often than not while cruising you are going to see a low cylinder airmass between .18g all the way up to .64g. This is the section of the table that you will want to modify.

The ZL1 base tune runs as high as 48.5 degrees of timing from what I have observed under normal circumstances and what you want to do here to take out some of that vibrational bite that is drone is lower the timing. I found that taking out an equivalent total of 13 degrees in certain sections of the timing map helped manage my drone and make it much more livable. I now see around 35 degrees of timing while driving under cruising and light load. It actually has helped a ton and here is the section where I made my changes:

The first two screenshots are the before area that I highlighted before I went in and made my reductions.





These are the after changes. Notice on the 3D map the area the high spikes were smoothed out after the changes were made and everything appears a bit more transitional.





After I implemented my changes I noticed that drone shut up quite considerably and made street driving and highway driving a bit more livable after the rest of the changes I have listed above had already been implemented and in place. My decibel meter tends to agree and so do my ears as well, which is the obvious ultimate tester in these sort of situations. Conversations within the cabin and the over the phone are easier to have now without feeling like I have to keep my foot off the pedal as much to manually change the exhaust tone and/ or play with the paddle shifters to keep the engine in a higher revving gear. My drone was occurring stronger around mild throttle under load around 1300- about 1800 RPM. My heads up display was always a visual indicator of how bad the drone was because if I was around a certain RPM range in certain load situations I would see the heads up display vibrate off the windshield and it would get worst and worse until the frequency resonance would stop, then the HUD would stop vibrating and normalize again.

Your results may vary and by no means will my solution work for you, but this is just a general idea on what could and what may work for you. Worst comes to worse, you can always revert back to the timing settings you originally had and either start over or count it as a wash.

Feel free to chime in with comments, questions, concerns, your setups, etc.
Given how much this forum has helped me over my last year and half of ownership. I just figured I would return the favor and hope this helps someone down the stretch!

[WhiteMale]

I learned about Drone when I did 2000 Grand Prix from the downpipe back and had Dynomax "super turbo" mufflers. The Frequency resonated in the cabin so bad that it hurt, headaches level drone. Being I had a Y pipe and a single 3" in the midsection, I had my shop fit in a cherry bomb glasspack about 24" long which seemed to tame it out and I didn't have any more drone problems.

Biggest thing I get from the Auto trans crowd is you can't keep the trans out of that RPM range of 1500 ish where it's the worst. Or the manual guys that row gears and get in the highest gear possible as fast as they can and RPMs just above idle (LOLOL).

Being at the time with my M6 1LE, I just avoided that RPM range, the car is kind of tellin you that it doesn't like being there, downshift and/or get your rev's up. I had a AWE touring system that worked as advertised with killing drone.

But with the A10...maybe you manual mode it to avoid the low RPM's. I have an MBRP muffler delete on this ZL1 but it has their Helmholtz(?) resonator that kills the drone very well. Its basically what you installed on your car.

[Z OH 6]

I just use the AWE resonated touring catback exhaust. No drone.

[dmcmahan60]

Originally Posted by Z OH 6

I just use the AWE resonated touring catback exhaust. No drone.

This

[WhiteMale]

AWE touring def works but I don't know with headers and all the OP's mods if he doesn't need a bigger solution.

[KingLT1]

I am running stock headers, cat delete pipes, Borla resonated X, Corsa NPP and have Zero drone. I can cruise down the hwy @ 70 with the valves closed and hear all the bass coming from my stereo. If you know anything about drone it will cancel the bass out on your speakers.

My Brothers H/C 2650 ZL1- catless LTH, Resonated X, stock NPP muffler...also no drone.

His H/C/2650 C7Z- catless LTH, resonated X, Billy Boat exhaust...also no drone.

You see the correlation here between these 3 different cars? They all have resonated X pipes and that is what cancels out the drone.

[18.2SS.1LE]

Long tubes, high flow cats to stock NPP with fuse pulled, no drone here.

[ZLRob]

Apparently I'm the one unfortunate SOB that gets and has had to deal with drone and no one else does.

I'll see myself out of here now.

[Mark R]

That is one fancy exhaust. I'm glad you got it all sorted.

[arpad_m]

Originally Posted by ZLRob

Apparently I'm the one unfortunate SOB that gets and has had to deal with drone and no one else does.

I'll see myself out of here now.

Drone or not, I very much appreciate your detailed writeup and saved it to PDF for reference (I'm about to make exhaust changes anyway, so may even need it soon). You even went to the trouble of making screenshots with appropriate highlighting. Thank you very much, good Sire.

[Z OH 6]

Originally Posted by WhiteMale

AWE touring def works but I don't know with headers and all the OP's mods if he doesn't need a bigger solution.

Kooks 2" headers here, GESI high flow cats, AWE resonated touring catback exhaust. No drone. It has a lot to do with the catback you choose and whether or not you use resonators.

[JSH]

Kooks long tube headers. No cats, crimp deletes, Kooks axle back. Lots of drone

[ZLRob]

Originally Posted by Z OH 6

Kooks 2" headers here, GESI high flow cats, AWE resonated touring catback exhaust. No drone. It has a lot to do with the catback you choose and whether or not you use resonators.

The problem is that most resonated setups usually use baffling and filling. When you make the power that our cars make it doesn't matter what brand you go with, the filling will eventually (and I mean on the sooner than the later side) shoot out of there just like the stock stuff does out of the OE suitcase.

Originally Posted by JSH

Kooks long tube headers. No cats, crimp deletes, Kooks axle back. Lots of drone

Hit it my boy!

If you haven't been doing the tuning yourself I'd be more than happy to give you a modified test file to see if it helps you at all. We only require about 80-90 HP under cruise conditions anyway and a lot of that is due to the fact that the superchargers require that much power to drive them. I would need your tune file to do that if you want to give this a shot though.

[Z OH 6]

Originally Posted by ZLRob

The problem is that most resonated setups usually use baffling and filling. When you make the power that our cars make it doesn't matter what brand you go with, the filling will eventually (and I mean on the sooner than the later side) shoot out of there just like the stock stuff does out of the OE suitcase.



Hit it my boy!

If you haven't been doing the tuning yourself I'd be more than happy to give you a modified test file to see if it helps you at all. We only require about 80-90 HP under cruise conditions anyway and a lot of that is due to the fact that the superchargers require that much power to drive them. I would need your tune file to do that if you want to give this a shot though.

Nope, no filling is going to blow out of the AWE resonators. Another good brand is Vibrant. Honestly the AWE resonators look just like Vibrant resonators. Two Vibrant 1794 or 1795 resonators installed in the tunnel would have likely done what you wanted to do.