Loud exhaust
Pro
Joined: Dec 1999
Posts: 690
Likes: 49
From: Atlanta Georgia
Might want to try headers or flip out the X Pipe and it should be a lot closer to the sound you're looking for.
Doug
Le Mans Master
Joined: May 2000
Posts: 8,729
Likes: 1,508
From: Redmond WA
The stock NPP system, when open, is pretty darned close to straight through. But you're always running through the factory cats which really do muffle things quite a bit. I fired it up in the shop with just the cats and manifolds (not exhaust whatsoever) and it wasn't all that crazy loud... certainly not "open header" loud.
I run a Corsa midpipe so lack the secondary cats, which made it somewhat louder, but it's the main cats that do the silencing. I'm personally not eager to remove cats from a modern car.
But if you're willing, going to long-tube headers with no cats will make it much, much louder.
I run a Corsa midpipe so lack the secondary cats, which made it somewhat louder, but it's the main cats that do the silencing. I'm personally not eager to remove cats from a modern car.
But if you're willing, going to long-tube headers with no cats will make it much, much louder.
Melting Slicks
Joined: Aug 2014
Posts: 2,746
Likes: 916
Even long tube headers with high flow cats will make it much much louder. The NPP mufflers are really a nice setup but most don't understand that they are nearly straight through when in track mode and think that aftermarket is the fix. The aftermarket will help, if you ditch the stock x-pipe for a cat free x-pipe.
I've said it multiple times on here that it's not the NPP mufflers quieting things down. It's all the junk between the engine and the mufflers. I've already been down this road with my 2009 Pontiac G8 GT and the solution to good and loud is long tube headers + highflow catted x-pipe with the stock NPP mufflers. The money spent on some of the aftermarket catback systems will pay for the headers and highflow catted x-pipe. If you don't want to tune your car because you're worried about warranty (that was my personal concern) I can attest that I have had great luck with the green cats not throwing a CEL code on my stock tune. With the NPP still fully functional, I can have loud when I want it and I can have "quiet" when I want it. It really is the best of both worlds.
I've said it multiple times on here that it's not the NPP mufflers quieting things down. It's all the junk between the engine and the mufflers. I've already been down this road with my 2009 Pontiac G8 GT and the solution to good and loud is long tube headers + highflow catted x-pipe with the stock NPP mufflers. The money spent on some of the aftermarket catback systems will pay for the headers and highflow catted x-pipe. If you don't want to tune your car because you're worried about warranty (that was my personal concern) I can attest that I have had great luck with the green cats not throwing a CEL code on my stock tune. With the NPP still fully functional, I can have loud when I want it and I can have "quiet" when I want it. It really is the best of both worlds.
Last edited by lakemg; May 4, 2017 at 07:44 PM.
