I just got my 07 new dual mode exhaust and I am loving it. I have one question, when i close the flaps and step on the gas they open up a little, Is this normal ??

 

Should open up at I believe 3500 RPM's.

 

hmm, don't think so. you don't have them vacuum operated, right? it's on mild to wild? in which case it should stay closed, I think. but wiser ones will chime in....

 

I have the mild to wild and revving the engine causes the flaps to open sligntly when in mild mode.

 

OK, I'll bite. You got new NPP or BB exhaust ...and what? .... a new Mild to Wild controller too? Which model and who installed it?

Add more info and you'll get more hits to your question.

 

I put this exhaust on my 07 as well and yes, they will open slightly when closed under certain conditions while under load as the engine vacuum does drop and they are vacuum operated (to close). It is not loud but give a slight growl when it happens which I happen to like.

The Vettes with the factory installed NPP exhaust have a small reserve vacuum tank that prevents this from happening. This info was posted here on the Forum about a year ago.

 

Nice mod and the only option I should have ordered on the 09

 

Factory NPP typically opens at about 3500rpm. M2W can keep it open all the time or let it stay closed from 0-3500.
If you are more descriptive about your install, you'd get better info in return.

 

If the system you purchased to do the install was an NPP in a Box kit that I sell then no it is not normal. If you did the install straight from the mufflers to the manifold with out a solenoid or tank, then yes it is. What you are experiencing is a drop off in vacuum pressure at the manifold where you tapped the vacuum source for the NPP muffler valves. The kit that I sell incorporates a solenoid in line to prevent this very thing from happening. It takes a certain amount of vacuum pressure to keep the valves closed and when you go to WOT that vacuum drops off. In your case it is dropping off enough to open the valves until the vacuum pressure can build back up again.

With an aftermarket install it will not function as it does in the OEM. The valves will not open at a given throttle or RPM as they do from the factory. With aftermarket the secret is in having a solenoid or supplemental storage tank available to make up the delta when the manifold pressure drops off.

 

talon90 a question.
I am looking to install the NPP exhaust option on my 2008 A6 including the vacuum line and control it with the Mild to Wild switch, but I take it by your post to make it operate like it was factory installed I also need NPP in a box, is that correct? Which I can get from you

 

Hi Paul,

It's actually a little more complicated than even that. The NPP as you know requires a vacuum souce to open and close the valves (just close really but anyway). The Mild 2 Wild only works on a system that has both vacuum present and an electronic solenoid since it that is what it is controlling. The NPP in a box kit provides both the solenoid and the addition of the M2W to electrically control the solenoid to allow user control of the valves.

The problem is that even with all of that hardware and technology the NPP on an aftermarket install (even a car that could have had an NPP from the factory 2008 or up). Will never be able to operate like an OEM install of the NPP. The NPP from the factory uses throttle position and driver intent to control when the valves will be open or closed. If the throttle is between 30% and 80% the valves will open at 3,500 rpm's. If throttle position is greater than 80% the valves will open at approximately 2,800. This is commanded by the BCM and PCM and will only have been installed in a car that came with NPP from the factory. If you add the NPP exhaust to even a 2008 or later Corvette it will not have the appropriate control software and it will not have the additional hardware in the form of the additional vacuum storage tank that will allow it to operate on RPM and throttle like from the factory and there is no way to add that in after the fact. The NPP in a box and a M2W is a great way to add an NPP exhaust to the car but you won't have the RPM opening of OEM. You will always be able to control with the remote from the M2W but our unit does not allow for RPM control.

 

I installed NPP on my 08 and used this npp control that lets me open the exhaust with a remote or have it open at 3200 rpm like the factory set up., got it from Ben at his site and he is very helpful if you have any issues.
Link to his site

http://www.shop.sunsetorangecreations.com/

 

Thanks Paul, great info and I also appreciate the PM. Thanks to you also George the more info I get the better decision I can make.