NPP Exhaust Sound Difference (M2M Retrofit) - Camaro5 Chevy Camaro Forum / Camaro ZL1, SS and V6 Forums

millatime84 · 03-27-2015, 10:03 AM

I just recently installed a NPP Catback on my 2010 SS and retrofitted my own NPP in a box. (can create a DIY later if needed) I was disappointed in the difference between open and closed. The sound difference at idle is minimal. At WOT you can noticeably tell the difference. Has anyone else experienced the same outcome either with a factory NPP or a Retrofit? Also has anyone opened a Camaro NPP muffler to see if the straight through pipe has holes in it similar to the early Z06 mufflers? If so I was thinking about having a muffler shop cap the the straight through pipe.

cottrellj2 · 03-27-2015, 10:28 AM

For the Factory NPP there is a fuse you can pull to keep it on the loud side. That's what I did and I will never go back. It does cause only one side to get dirty on your pipes which is one way to confirm that the flap is staying open.

There is a DIY guide on the forums, but I doubt its the same for a retrofit.:
http://www.camaro5.com/forums/showth...=npp+fuse+pull

You might need a mild to wild (or something like it) switch for it.

ST1LE · 03-27-2015, 11:10 AM

Quote:

Originally Posted by millatime84

I just recently installed a NPP Catback on my 2010 SS and retrofitted my own NPP in a box. (can create a DIY later if needed) I was disappointed in the difference between open and closed. The sound difference at idle is minimal. At WOT you can noticeably tell the difference. Has anyone else experienced the same outcome either with a factory NPP or a Retrofit? Also has anyone opened a Camaro NPP muffler to see if the straight through pipe has holes in it similar to the early Z06 mufflers? If so I was thinking about having a muffler shop cap the the straight through pipe.

In stock form there probably is not a huge difference. The video below is when my car had headers and high flow cats. It is quite noticeable, especially in my parking garage. The video makes is sound less drastic, as when open it gets WAY deeper than when closed.

Now that I have a cam, open vs. closed is an even bigger difference. Open is insanely loud and deep, even at idle(love it), and closed is much more tame and bearable for those that don't love it like we do.

millatime84 · 03-27-2015, 11:48 AM

I have a similar setup to what you had. Kooks Header and Highflow cats. I guess my next mod needs to be a cam. I just thought there would be a more noticeable difference.

malave7567 · 03-27-2015, 11:53 AM

Quote:

Originally Posted by millatime84

I just recently installed a NPP Catback on my 2010 SS and retrofitted my own NPP in a box. (can create a DIY later if needed) I was disappointed in the difference between open and closed. The sound difference at idle is minimal. At WOT you can noticeably tell the difference. Has anyone else experienced the same outcome either with a factory NPP or a Retrofit? Also has anyone opened a Camaro NPP muffler to see if the straight through pipe has holes in it similar to the early Z06 mufflers? If so I was thinking about having a muffler shop cap the the straight through pipe.

You got it to stay closed on idle (Camaro defaults to open on idle)? I always guessed that was possible with some wiring... and it's what I always wanted to be able to do when I had my LS3 with NPP.

millatime84 · 03-27-2015, 12:50 PM

Quote:

Originally Posted by malave7567

You got it to stay closed on idle (Camaro defaults to open on idle)? I always guessed that was possible with some wiring... and it's what I always wanted to be able to do when I had my LS3 with NPP.

yes with how i retrofitted my exhaust with a powered solenoid, I can open and close it at idle.

03-27-2015, 10:03 AM	#1
millatime84 Drives: 2010 2SS IOM/IOM Join Date: Feb 2014 Location: Normal,IL Posts: 100	NPP Exhaust Sound Difference (M2M Retrofit) I just recently installed a NPP Catback on my 2010 SS and retrofitted my own NPP in a box. (can create a DIY later if needed) I was disappointed in the difference between open and closed. The sound difference at idle is minimal. At WOT you can noticeably tell the difference. Has anyone else experienced the same outcome either with a factory NPP or a Retrofit? Also has anyone opened a Camaro NPP muffler to see if the straight through pipe has holes in it similar to the early Z06 mufflers? If so I was thinking about having a muffler shop cap the the straight through pipe.

03-27-2015, 10:28 AM	#2
cottrellj2 Blue Ray SCPO Drives: 2013 Camaro 2SS/RS Join Date: Mar 2013 Location: San Diego, CA Posts: 61 View My Garage	For the Factory NPP there is a fuse you can pull to keep it on the loud side. That's what I did and I will never go back. It does cause only one side to get dirty on your pipes which is one way to confirm that the flap is staying open. There is a DIY guide on the forums, but I doubt its the same for a retrofit.: http://www.camaro5.com/forums/showth...=npp+fuse+pull You might need a mild to wild (or something like it) switch for it. __________________

03-27-2015, 11:48 AM	#4
millatime84 Drives: 2010 2SS IOM/IOM Join Date: Feb 2014 Location: Normal,IL Posts: 100	I have a similar setup to what you had. Kooks Header and Highflow cats. I guess my next mod needs to be a cam. I just thought there would be a more noticeable difference.