[Emoto]

Originally Posted by KingLT1

There are a couple ways to keep the valves closed on startup.

One is by setting the exhaust to stealth through the infotainment but then the valves will stay closed in all modes(touring/sport/track/Snow Ice).

The second option is putting the car in accessory mode and selecting Snow/Ice mode before starting the engine. Snow/Ice is stealth mode and the NPP valves remain closed at startup and all throttle inputs.

Touring still lets the valves open on initial start-up then closes.

If you are not concerned about warranty or out of warranty, you can use Hp tuner software and custom tune how the NPP exhaust valves operate for all modes.

Am I mistaken, or isn't the exhaust one of the various settings you can tweak for each mode right through the center screen?

FWIW, I just leave the garage door down when I start mine, so that the initial bark doesn't awaken my very nice retired neighbors across the street. Within a short period of time, it quiets down. By the time I have my phone in the holder and connected, I'm good to go.

[BluinSC]

Yes you can change the exhaust steering, and if you have MRC, suspension

[Aragorn]

Originally Posted by Emoto

Am I mistaken, or isn't the exhaust one of the various settings you can tweak for each mode right through the center screen?

FWIW, I just leave the garage door down when I start mine, so that the initial bark doesn't awaken my very nice retired neighbors across the street. Within a short period of time, it quiets down. By the time I have my phone in the holder and connected, I'm good to go.

I think this is a good idea, but there was an extremely long thread a while back about the dangers of doing exactly this. LOL!

[Nukezone]

Did anyone else get a lot of codes after changing the exhaust? I put on catless longtube headers and X pipe, removing the valve control (I guess it’s called NPP) and no I have some codes P12E3 P12E7 P123EB P12F4 P12F8, and I have a misfire in number 8 shop says it can happen since I have the valve controlls off the exhaust. Can I just pull the fuse and clear codes and won’t have the problems anymore?
Ps my first American car ever

[sactownbwoy]

Originally Posted by Nukezone

Did anyone else get a lot of codes after changing the exhaust? I put on catless longtube headers and X pipe, removing the valve control (I guess it’s called NPP) and no I have some codes P12E3 P12E7 P123EB P12F4 P12F8, and I have a misfire in number 8 shop says it can happen since I have the valve controlls off the exhaust. Can I just pull the fuse and clear codes and won’t have the problems anymore?
Ps my first American car ever

Its the headers or AFM if your car is an auto. I did just an axleback and have no codes. My npp controllers are tucked away. NPP is controllers are on the tailpipe of the exhaust.

[NYTMARE23]

Originally Posted by sactownbwoy

Its the headers or AFM if your car is an auto. I did just an axleback and have no codes. My npp controllers are tucked away. NPP is controllers are on the tailpipe of the exhaust.

Glad to hear this!! I'm trying to get an axle-back, so I was worried I was going to have issues. On the other hand if the one I want falls through, I've been talking to an AWE rep and he said I can get an axle-back touring edition, but it gets rid of the valve function so I'm a bit worried about that system throwing codes. He assured me that it wouldn't so I don't know? . Anyone else have the AWE Touring Edition Axle-back with no issues(about throwing codes due to the valves being disabled?)

[B84GTX]

Originally Posted by Shredstone

I did spend the money on Borla S-Type. The start up is loud. In the mornings, I typically fire it up with the garage door shut. All other times, I love it. It's especially sweet hearing it fire up from a distance in the parking garage at work!

Did you get an axle back or a cat back system?
Do you have link to the product you bought?

[Streetrod782]

Originally Posted by NYTMARE23

Glad to hear this!! I'm trying to get an axle-back, so I was worried I was going to have issues. On the other hand if the one I want falls through, I've been talking to an AWE rep and he said I can get an axle-back touring edition, but it gets rid of the valve function so I'm a bit worried about that system throwing codes. He assured me that it wouldn't so I don't know? . Anyone else have the AWE Touring Edition Axle-back with no issues(about throwing codes due to the valves being disabled?)

I just installed the AWE axel back touring edition about 3 weeks ago and no codes. Just zip tie the controllers up and put some electrical tape over the ends. The black tips are on back order just fyi it will come with the chrome. And it’s pretty damn loud over stock.

[Saberscar223]

Originally Posted by LT4

NPP delete will have no affect on cold start bark. Even stock exhaust has it. And the valves will be open on start up regardless of if you parked it in Steath mode the night before.

Some quieting tips:

• Park the car ass in.
• If you have an A10, as soon as you start it up in the morning, put it in D or R and sit there with foot on brake for a minute or 2 until she settles down.
• If you have a M6, well.... sorry.

I sold my Bolrlas (S-Type) because of early morning start ups. Went back to stock with a couple of $10 sleeve clamps, so keep the stock exhaust!

This is false if you turn off the car in stealth mode it starts up with the Valves close you can even hear them shut right before ignition

[lt4camaro]

Originally Posted by 95 imp

It's not the firing order. It's the flat plane crank.

Only the GT350 has the flat plane crank.

[NYTMARE23]

Originally Posted by Streetrod782

I just installed the AWE axel back touring edition about 3 weeks ago and no codes. Just zip tie the controllers up and put some electrical tape over the ends. The black tips are on back order just fyi it will come with the chrome. And it’s pretty damn loud over stock.

Ok. Sounds great! Thank you for the info and heads up!

[arpad_m]

Originally Posted by 95 imp

It's not the firing order. It's the flat plane crank.

Originally Posted by Memphis SS

The flat plane crank motor only comes in the Shelby mustang GT350

95 imp is right on the money, and indeed the GT350 has a special flat plane crank engine that sounds a bit like a cross-plane crank.

IMO that Voodoo thing in the GT350 is the only one that arguably sounds as good or even better than the cross-plane crank in the LT1/LT4. Here is an excellent video for some context, definitely worth watching:

[Caerus]

Originally Posted by arpad_m

IMO that Voodoo thing in the GT350 is the only one that arguably sounds as good or even better than the cross-plane crank in the LT1/LT4. Here is an excellent video for some context, definitely worth watching:

Thanks for posting that video; it was an interesting watch.

[LT1gen6]

Originally Posted by arpad_m

Here is an excellent video for some context. .

Yes, thanks for posting the video. It has to be at the top of my all-time faves. ICE design and history are amazing, to the extent of engineering and art being elevated together. Makes me appreciate ICE to a greater extent than I imagined. Wow! Totally opposite that EV off-on motors.