Npp mufflers and boost question
Thread Starter
Pro
Joined: Mar 2015
Posts: 719
Likes: 50
From: Burbank California
Npp mufflers and boost question
One of my Npp mufflers developed a nasty rattle. After some research I found out the baffles can blow out. I'm at 14# of boost. Before I go and get other Npps and possibly have the same result is like to get your opinion on weather or not staying with the same mufflers is ok. I have the mild to wild hardware and like the adjustability of the sound. For those that are boosted and have Npp please chime in on the durability. Thanks!
Racer
Joined: Aug 2011
Posts: 289
Likes: 3
From: Alamogordo NM
One of mine developed a rattle shortly after I boosted it. I just kept driving the hell out of it, and it eventually fixed itself. I'm assuming the baffle wedged itself somehow, but it hasn't rattled since.
Thread Starter
Pro
Joined: Mar 2015
Posts: 719
Likes: 50
From: Burbank California
Detoxx, I'm glad your having good luck with yours. Badass car by the way. Dubs, your not the first to say the rattle went away. I'm torn cuz I've got different ones I could get for $350 I'd have to get them installed too. The rattle is getting a lot worse. Maybe something will wedge or break loose. Anybody else have any experience with this?
Le Mans Master
Joined: Apr 2011
Posts: 7,821
Likes: 412
From: Montreal
St. Jude Donor '13
Originally Posted by c6 monkey
I'm sure it doesn't help to have hollowed out cats and the fiberglass removed from the mufflers. Realcanuck, 20 lbs is rockin it. How long have your guys npps been on and ok?
Pro
Joined: Mar 2016
Posts: 562
Likes: 66
Wow I completely forgot I had a bad rattle under light throttle (parking lot speeds) until I read your post. I'm boosted and it fixed itself also! Granted mine rattled prior to boost most likely from hitting a pot hole.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Advanced
Joined: Jul 2014
Posts: 53
Likes: 4
From: Houston Texas
This happened to my NPP setup after headers with 9 psi. I had a local guy cut them open and do the muffler mod, he then stitch welded the cracks back up and reinforced the front/back walls with angle iron. No issues since the repair work was done.
Race Director
Joined: May 2004
Posts: 16,667
Likes: 1,209
From: Raleigh, NC
St. Jude Donor '15
No issues on mine either, mine open once near boost though. Not using the controller, connected directly to vacuum source
Last edited by schpenxel; Dec 18, 2017 at 08:44 PM.
Racer
Joined: Oct 2011
Posts: 475
Likes: 3
From: Jacksonville TX
I had rattles in mine before boost.
https://www.corvetteforum.com/forums...p-muffler.html
Member Atomic C6 added to my post on what he did to fix his. I did this myself. I have had no issues with mine since.
https://www.corvetteforum.com/forums...p-muffler.html
Member Atomic C6 added to my post on what he did to fix his. I did this myself. I have had no issues with mine since.
Pro
Joined: Mar 2011
Posts: 569
Likes: 73
From: Colts Neck NJ
Had that set up for years. 16lbs of boost. Usually ran the NPP open but, on 4 occasions that I can recall, I made a WOT 2 - 4 gear pull with it closed. No muffler issue as a result.
I do know that in really high horsepower/boost applications (1xxx whpr cars), the NPP blades have been bent open by the force.
I do know that in really high horsepower/boost applications (1xxx whpr cars), the NPP blades have been bent open by the force.
Pro
Joined: Mar 2011
Posts: 569
Likes: 73
From: Colts Neck NJ
Team Owner
Joined: Nov 2007
Posts: 24,035
Likes: 2,342
From: Gilbert AZ
I know he killed a set of fusions or two, and I killed a set of fusions, along with 5-6 other people, but in 20k miles with stock NPP at 1000+ never an issue. Now the fusions lasted ~800 miles or something silly.
Drifting
Joined: Sep 2005
Posts: 1,328
Likes: 35
From: Bridgewater NJ
