thomaswat

I just had a couple of NPP mufflers installed on my '08 standard, and was excited to hear the much anticipated change in exhaust sound. With both valves open it is somewhat louder though not much. Closed is very quiet. What surprised me was how quiet it is with the valves open. I was expecting something like glasspacks. The sound I'm getting is deeper which I like, but much more quiet than expected. There is some drone which I anticipated, and I can live with that, or close the valve. I know I'm old and my hearing is not the greatest, but I was hoping for something with a lot more gusto.
Are all of these mufflers this quiet, or is it me ? I guess the old hot rod in me is alive and well. I have a few classic cars in the "hot rod" catagory, and I expected more of that type of sound. I guess I'm not really disappointed, just surprised.
Tom

C5kid

ditch the CATs and put some LT headers on, it makes a big difference.

flange

They really arent that loud like a glasspack. To me, even with the roof down, they are somewhat quiet as well, in fact, they make more noise coming off of the throttle until they close.

Flh Den

Did you put a complete new NPP system in with the vacuum lines and all? If you do have the vacuum tap and wanted to stay with dual mode exhaust but with a more aggressive sound the Billy boat fusions are the
way to go. Beautiful system.

laconiajack

Tom - Get split stainless steel collars and clamp them on the stems of the valve actuators to hold the valves open about 1/4" minimum all the time, except when you have your foot to the floor above 4,500 rpm when they will open all the way. That way you will then hear beautifully sounds all the time without being obnoxiously loud. Don't be a jerk and pull your NPP fuse; Corvette owners have a bad enough reputation already.

Bedouin

Better yet, do the add-a-fuse switch so you can turn it on & off from inside the car...costs about $10

dvilin

Although alot better than the closed position or the stock exhaust. I have the M2W and just leave it in the open position 100% of the time. Not a bad sound at all.

LFZ

Yes they are that quiet...even with valves open all the time like the jerks do.

shawn672

Yup! 3x louder than stock but still very quiet

11yellowgscpe

I run mine open all the time and they are almost as loud as my friends 07 with Corsa Sports

Grand Sport Jim

"Better yet, do the add-a-fuse switch so you can turn it on & off from inside the car...costs about $10"

Not familiar with this. Can anyone clarify how to add this mod?

QUAKEJAKE

427 jerk here plus added the "muffler mod". Nice all the time.

Gearhead Jim

That would be a home made version of the "Mild to Wild" system that allows you to open the NPP flaps at any time.

We have the NPP dual mode exhaust on our 2009, the first mod i did was the MTW with a foot switch, and we love it.

m kraz

pull the fuse

Flh Den

Don-Vette

Pulled the fuse when I got my GS and never put it back in. Pure music to me!

thomaswat

Thanks guys. I guess my hearing isn't as bad as I thought. They are indeed quieter than I expected.
I assume that pulling the fuse leaves them open all the time. Is that correct ?
Also, I noticed that some of you think leaving them open all the time makes you a "Jerk". As quiet as they are, what's what's wrong with them open all the time ? Unless you are accelerating hard, not one else hears them anyway, and as quiet as they are, I can't imagine anyone would be offended.
I have several resto-mods and on occasion my wife and I will drive one of them coast to coast. The sound of their dynomax turbo mufflers, is music to my ears. I love the "noise". Never thought of someone thinking I was a jerk. Most just appreciate the car and seem to enjoy the sound.
Different strokes for different folks I guess.
Tom

spdkilz911

Yes, pulling the fuse leaves them open all the time. There is some drone at lower RPM's. I have the M2W switch and it stays open 99% of the time. When my wife drives it, which is very rare, she closes it. It's nice to have the option. I'm thinking about the B&B system. I had his system on my 99 Z28. This one with the dual mode has me thinking.

VatorMan

The only time I close my flaps is when the wife is in the car-unless she starts talking then I open them again.

Richie Fazio

Put Corsa Sports on. They sound better IMO.