Help, looking to quiet LT headers and cam - Page 2

CHEM2010 · 10-12-2020, 09:10 PM

Baddawg53 · 10-13-2020, 12:30 AM

Quote:

Originally Posted by Blackkaz04

The SS 1LE I recently purchased is too loud for my local track. The build is a btr cam, 1 7/8” headers cat delete and the stock NPP exhaust., I’m looking to tone the car down some...not only is it too loud for the track but the crackling and burbling in the exhaust sounds about like gunshots. Anyways, I’m looking at kooks 12-19” race mufflers to add in front on the NPP exhaust.

Has anyone done this? Any other ideas? What’s the difference between resonators and mufflers. I found force resonators for the same price as the kooks mufflers....

I have heads/cam/LT's, borla atak with NPP. To get under track limits I added the borla resonator and the stock NON NPP muffler. I'm sure I'm sacrificing a few horsepower, but it's definitely under the 103 limit and I'm confident bit will be under 95. Trust me, ditch the NPP and go stock non NPP ... It dropped 25+ db revving in my driveway.

Blackkaz04 · 10-13-2020, 05:31 AM

Quote:

Originally Posted by Baddawg53

I have heads/cam/LT's, borla atak with NPP. To get under track limits I added the borla resonator and the stock NON NPP muffler. I'm sure I'm sacrificing a few horsepower, but it's definitely under the 103 limit and I'm confident bit will be under 95. Trust me, ditch the NPP and go stock non NPP ... It dropped 25+ db revving in my driveway.

I really want to retain some of the NPP function. But we’ll see. after a lot of reading I ordered a magnaflow x-pipe muffler. I think it may do the trick.

https://www.carid.com/magnaflow/stai...vD_BwE#reviews

Baddawg53 · 10-13-2020, 07:53 AM

I spent something like 800 bucks and welded my own custom exhaust with two mufflers per side, now I have a bunch of spare parts in my garage.

I swap out this big suitcase for my atak mufflers after my track day, it's really pretty easy. I don't think you'll find a muffler as quiet as the stock one but I'm definitely gonna be following this to see if it works for you.

ST1LE · 10-13-2020, 08:08 AM

Quote:

Originally Posted by Blackkaz04

I really want to retain some of the NPP function. But we’ll see. after a lot of reading I ordered a magnaflow x-pipe muffler. I think it may do the trick.

https://www.carid.com/magnaflow/stai...vD_BwE#reviews

So, I tried this when I had a similar set up as you on my 5th Gen. Cam, LT's, cats into factory NPP, and i installed the Magnaflow X-pipe. It worked wonderfully to quiet the exhaust down, but for me it added drone.

That really may have just been in my application, so you may have better luck, and I think you will.

Let us know how it goes, I will be in your boat one day.

Blackkaz04 · 10-13-2020, 08:53 AM

Yea, I do worry about the exhaust droning but if it does badly maybe I’ll add some resonators

Fraxum · 10-13-2020, 12:45 PM

Quote:

Originally Posted by KingLT1

Install some 16" resonators in the x pipe.

Agreed resonators. They worked great on my 5th gens with LTs. On my '16 SS running LTs, running them even with cats through the NPP suitccase, was horrible sounding.

No drone though with NPP.

avalonandl · 10-13-2020, 03:43 PM

https://www.jegs.com/i/Dynomax/289/1...IaArVpEALw_wcB

Blackkaz04 · 10-13-2020, 09:19 PM

Quote:

Originally Posted by avalonandl

https://www.jegs.com/i/Dynomax/289/1...IaArVpEALw_wcB

Have you run this Xpipe on the 6th gen camaro? It’s almost 10 inches wide....not sure if it would fit in the exhaust tunnel

avalonandl · 10-16-2020, 09:25 AM

Quote:

Originally Posted by Blackkaz04

Have you run this Xpipe on the 6th gen camaro? It’s almost 10 inches wide....not sure if it would fit in the exhaust tunnel

No was making a suggestion

Blackkaz04 · 10-16-2020, 09:30 PM

Quote:

Originally Posted by avalonandl

No was making a suggestion

Gotcha. Yeah, the magnaflow I posted above is about the same thing I think....I last minute decided to add kooks round race mufflers before the NPP exhaust based on the suggestion from the shop that installed the cam. If that doesn’t do it I’ll try the xpipe muffler...

RobbyBeefcake87 · 10-19-2020, 07:26 AM

Quote:

Originally Posted by Blackkaz04

Thanks. I think I’m going to give the kooks Round mufflers a shot. Now to decide between the 14” and 19”. I’ll post back my results.

What Is a Resonator? While mufflers reduce the exhaust volume, resonators tune the exhaust for a more pleasant sound. Resonators will remove some of the raspy and high-pitched noises from the exhaust but won't do anything to muffle the volume

My opinion is you almost need both with LTs and the NPP exhaust. TBD

Do you have a link to the Kooks 4' mufflers? Looking for something like this for an e46 ls1 swap car so the size of the kooks won't be an issue since I'll only be running one (single exhaust).

EDIT: Never mind, just looked them up real quick.

cmitchell17 · 10-19-2020, 01:08 PM

Does anyone have a picture of what the stock non NPP muffler looks like? I wonder if its the same dimensions? I would really like to see one cut open.

Also I believe there is a lot of sound reduction when revving at idle from NPP to non NPP because the valves are calibrated to be open when the car is not moving so it will be loud when you rev it and people will be impressed, but then close while driving along normally.

I have tried to change the valve positions around with HP Tuners, but I mostly found that there is no in between, its either open and obnoxiously loud at WOT, or closed 100%. There is something about exhaust that sounds good below about 60% throttle, then once you go above that at WOT, the sound quality just turns awful.

10-13-2020, 03:43 PM	#22
avalonandl Drives: 2019 ZL-1 Join Date: Feb 2009 Location: Troy, MI & Naples, FL Posts: 2,019	https://www.jegs.com/i/Dynomax/289/1...IaArVpEALw_wcB __________________ 2019 ZL-1 Acquired 4/23/21 at 6300 miles. Riverside Blue, A10, PDR. Traded in 2017 2SS with 6M and 32k miles. Continental Extreme Contact Sports. Now has 10,000 miles... 2012 Yukon XL Denali w/ 6.2 AWD

10-12-2020, 09:10 PM	#15
CHEM2010 Drives: 2018 chevy camaro ss 1le Join Date: Sep 2020 Location: charleston wv Posts: 8

10-13-2020, 07:53 AM	#18
Baddawg53 Drives: 17 hyper blue 2SS M6 Join Date: Mar 2018 Location: NorCal Posts: 594	I spent something like 800 bucks and welded my own custom exhaust with two mufflers per side, now I have a bunch of spare parts in my garage. I swap out this big suitcase for my atak mufflers after my track day, it's really pretty easy. I don't think you'll find a muffler as quiet as the stock one but I'm definitely gonna be following this to see if it works for you.

10-13-2020, 08:53 AM	#20
Blackkaz04 Drives: 2006 Z06 Join Date: Sep 2010 Location: DC area Posts: 859	Yea, I do worry about the exhaust droning but if it does badly maybe I’ll add some resonators

10-19-2020, 01:08 PM	#27
cmitchell17 Drives: 17 2SS, 8L90, Cam, Heads, E85 Join Date: Dec 2016 Location: US Posts: 1,201	Does anyone have a picture of what the stock non NPP muffler looks like? I wonder if its the same dimensions? I would really like to see one cut open. Also I believe there is a lot of sound reduction when revving at idle from NPP to non NPP because the valves are calibrated to be open when the car is not moving so it will be loud when you rev it and people will be impressed, but then close while driving along normally. I have tried to change the valve positions around with HP Tuners, but I mostly found that there is no in between, its either open and obnoxiously loud at WOT, or closed 100%. There is something about exhaust that sounds good below about 60% throttle, then once you go above that at WOT, the sound quality just turns awful.

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