Is your NPP exhaust getting louder?
06-05-2010, 02:03 PM
#1
Melting Slicks
Thread Starter
Is your NPP exhaust getting louder?
Might be my imagination, but it seems my M2W equipped NPP exhaust sounds louder than it did when it was brand new. A buddy of mine put a brand new NPP system on his '05 and it's a LOT quieter than mine, but I figured it could be the LS2 engine difference.
I've got 22,000 miles.
I've got 22,000 miles.
Last edited by SSTEVEGS; 06-05-2010 at 02:03 PM. Reason: added mileage info
06-05-2010, 02:22 PM
#2
Racer
Member Since: Dec 2009
Location: Auburn Alabama
Posts: 285
Likes: 0
Received 0 Likes
on
0 Posts
if you have stock NPP exhaust with no controller I believe it starts out closed and only opens after you pass 3500 rpms. I could be wrong on the numbers but if you set your M2W to keep your exhaust open all the time, it will be louder than a non controlled NPP due to the fact that you control the baffles on the exhaust versus the ECU and Chevy programming to dictate the opening and closing.
06-05-2010, 03:12 PM
#3
Team Owner
Member Since: Sep 2000
Location: Far NW 'burbs of Chicago
Posts: 23,937
Received 2,051 Likes
on
1,362 Posts
St. Jude Donor '13
My NPP seemed to get louder after I installed the MTW foot switch.
06-05-2010, 04:14 PM
#6
Pro
Member Since: Mar 2010
Location: NY
Posts: 580
Likes: 0
Received 0 Likes
on
0 Posts
I just have the fuse pulled, so open all the time. Car is a lot louder when you start with a cold engine. What I have noticed is that some of the plastic in the dash and something in the rear hatch are starting to vibrate with the exhaust, real, real annoying. ITs like the are in tune with the exhaust, almost making me think about putting the fuse back in.
06-05-2010, 05:40 PM
#7
Team Owner
Member Since: Jun 2005
Location: Northern, VA
Posts: 46,104
Received 2,481 Likes
on
1,944 Posts
St. Jude Donor '15
"In honor of jpee"
no, but mine are partially open with the collars on all the time. very very partial tho...and hasn't changed in a year or so.
06-06-2010, 01:28 AM
#9
Safety Car
Mine seems a bit quieter now... especially since I've added an Exotic Vette partition and a Lloyd's cargo mat. 
I've heard some folks swear that their exhaust sound changes over time -- not just Corvettes. Typically it gets louder. So I believe you.
For peace of mind, make sure the NPP is working properly. Sit behind the car with the engine running and use the M2W to make sure the NPP valves fully open & close. The "quiet" mode might be compromised if the valves don't fully close.
And Mojoman might be right... been swimming lately? Maybe wax build-up in your ear got washed out.
I've heard some folks swear that their exhaust sound changes over time -- not just Corvettes. Typically it gets louder. So I believe you.
For peace of mind, make sure the NPP is working properly. Sit behind the car with the engine running and use the M2W to make sure the NPP valves fully open & close. The "quiet" mode might be compromised if the valves don't fully close.
And Mojoman might be right... been swimming lately? Maybe wax build-up in your ear got washed out.
06-06-2010, 04:55 AM
#13
Safety Car
Member Since: May 2006
Location: Providence Forge, VA
Posts: 4,254
Received 114 Likes
on
46 Posts
St. Jude Donor '08-'09-'10-'11-'12
To give you a serious answer, mine seems louder than it did initially. I've left it open for couple of years but I have no measurements to confirm it.
06-06-2010, 05:16 AM
#14
Melting Slicks
I've noticed mine was louder. But I attribute it to the hot humid days, as opposed to when I got it on Halloween last year.
I asked about other volume levels because sound pressure levels change with humidity....and he lives in the South.
I asked about other volume levels because sound pressure levels change with humidity....and he lives in the South.
06-06-2010, 05:35 AM
#15
Pro
Member Since: Dec 2009
Location: Seattle Wa
Posts: 572
Likes: 0
Received 0 Likes
on
0 Posts
I just have the fuse pulled, so open all the time. Car is a lot louder when you start with a cold engine. What I have noticed is that some of the plastic in the dash and something in the rear hatch are starting to vibrate with the exhaust, real, real annoying. ITs like the are in tune with the exhaust, almost making me think about putting the fuse back in.
06-07-2010, 11:31 AM
#16
Melting Slicks
Thread Starter
Mine seems a bit quieter now... especially since I've added an Exotic Vette partition and a Lloyd's cargo mat.
I've heard some folks swear that their exhaust sound changes over time -- not just Corvettes. Typically it gets louder. So I believe you.
For peace of mind, make sure the NPP is working properly. Sit behind the car with the engine running and use the M2W to make sure the NPP valves fully open & close. The "quiet" mode might be compromised if the valves don't fully close.
And Mojoman might be right... been swimming lately? Maybe wax build-up in your ear got washed out.
I've heard some folks swear that their exhaust sound changes over time -- not just Corvettes. Typically it gets louder. So I believe you.
For peace of mind, make sure the NPP is working properly. Sit behind the car with the engine running and use the M2W to make sure the NPP valves fully open & close. The "quiet" mode might be compromised if the valves don't fully close.
And Mojoman might be right... been swimming lately? Maybe wax build-up in your ear got washed out.
Thanks for the advice!
06-07-2010, 11:40 AM
#17
Safety Car
Member Since: Mar 2009
Location: Northeast MA & Mad Beach FL
Posts: 4,101
Received 716 Likes
on
436 Posts
Most exhausts will get a little louder as they break in.
Wouldn't say it's a real lot, but, I noticed my NPP got a little louder after around 3000 miles.
Hot or Cold Weather can have a small affect on loudness also with the density of the air changing the combustion
Wouldn't say it's a real lot, but, I noticed my NPP got a little louder after around 3000 miles.
Hot or Cold Weather can have a small affect on loudness also with the density of the air changing the combustion
06-07-2010, 03:10 PM
#18
Pro
Member Since: Mar 2010
Location: NY
Posts: 580
Likes: 0
Received 0 Likes
on
0 Posts
LOL. Funny, car has less than 1000 miles and does have way more buzzing (that is the exact description) then most of my work trucks that have over 100k on them.
06-07-2010, 03:13 PM
#19
Team Owner
06-07-2010, 03:14 PM
#20
Drifting
Member Since: May 2008
Location: LA Area CA
Posts: 1,358
Likes: 0
Received 0 Likes
on
0 Posts
If you have M2W and it is louder when it is closed then you are probably having vacuum issues. Seriously, mine was doing this too. The vacuum line that they supply is a lil big and it will expand over time and get bigger. Just put a smaller vaccum line in and it will fix everything. Just got mine redone a few weeks ago and it's back to normal now 