NPP Muffler Install
Thread Starter
Intermediate
Joined: Aug 2019
Posts: 24
Likes: 3
From: Millsboro, DE
NPP Muffler Install
I have a set of NPP Mufflers to install on my Base 2009 with a Cam, LT Headers, High Flow Cats with X-Pipe. I have not received the NPP In A Box that I ordered. If I install the Mufflers now and the NPP in A Box later; will the Muffles be in in Quiet or Loud Mode ?
Melting Slicks
Joined: Oct 2015
Posts: 3,299
Likes: 769
From: Mead Wash
2020 C6 of the Year Finalist - Modified
C6 of Year Finalist (appearance mods) 2019
Npp
It will be easier when you have the old mufflers off to drill the small whole in the RR cubby hole and run the vacuum line. Wait and do it all at once.
Le Mans Master
Joined: Dec 2005
Posts: 6,999
Likes: 1,685
From: Southeast TX
You can run a vacuum line back there just as the instructions tell you. You just don't have the box. Hooked direct to manifold vacuum, they will be quiet at cruise and loud when you get in to the throttle. My used box that I bought on the forum never worked. I just by passed the box and run it off of straight manifold vacuum. I actually like it that way. You don't have to push a button to get loud. It gets loud instantly when you mat the throttle. Quiet other wise.
You have to run vacuum back there regardless. Just run it through the right rear cubby. You can run it like mine until the box arrives. You just cut the line and install the box in the cubby. Run power to it and you're done.
If you want it in the loud mode just cruising around, then yeah, you need the box. I just don't feel the need to be loud when I'm not wanting to accelerate hard. And I don't have to push a button.
You have to run vacuum back there regardless. Just run it through the right rear cubby. You can run it like mine until the box arrives. You just cut the line and install the box in the cubby. Run power to it and you're done.
If you want it in the loud mode just cruising around, then yeah, you need the box. I just don't feel the need to be loud when I'm not wanting to accelerate hard. And I don't have to push a button.
Race Director
Joined: Sep 2007
Posts: 16,557
Likes: 2,106
From: Peoria/Phoenix AZ
C6 of Year Finalist (performance mods) 2019
Actually, the hole can be drilled by hand from the inside of the cubby, since the cubby material doesn't even require any more power than your fingers to turn the drill bit. Ask me how I know.
Tech Contributor
Joined: Mar 2003
Posts: 12,094
Likes: 197
From: Colorado Springs, CO
St. Jude Donor '08-'09-'10-'11
As others have said, it will be in the open (loud) mode but some Z06 and Grand sport owners leave it in that mode all the time. I had added the Z06 exhaust to my car and it added a bass note to it but it wasn't offensively loud to me. I like the sound of electric cars so I prefer quiet. That said, open mode didn't annoy me. I too had the NPP in a box mod.
Thread Starter
Intermediate
Joined: Aug 2019
Posts: 24
Likes: 3
From: Millsboro, DE
Thanks for all of your input; I will wait to have the NPP Mufflers and NNP In the Box installed the same time; I ordered one NPP in the Box on 7/22/and another on 7/28 and neither has shipped yet. Not very happy with either of the Forum Vendors that I ordered from.
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