Al and Pete Fuschion - First Sounds

[-=Jeff=-]

I think they would as they too are vacuum controlled to my knowledge anyway

[XfireZ51]

Originally Posted by -=Jeff=-

I think they would as they too are vacuum controlled to my knowledge anyway

Stock C6 tips not bi-modal. The C6 muffs are single exit and split into 2 tips. They're really not close. However, GS uses bi-modals also.

Actually looking at the tips they look similar.
SET OF CORVETTE C6 FACTORY EXHAUST MUFFLERS 2005-12

[-=Jeff=-]

Originally Posted by XfireZ51

Stock C6 tips not bi-modal. The C6 muffs are single exit and split into 2 tips. They're really not close. However, GS uses bi-modals also.

Correct but RPO Option NPP is for Bi-modal exhaust on regular cars.. GS/AR1 and Z06 I believe have Bi-modal standard

http://www.vetteweb.com/features/vem.../photo_12.html

Q: What is the NPP Dual Mode Exhaust Option and how does it work??
NPP is the Regular Production Option (RPO) code for the Dual Mode Exhaust Option first offered to non-Z06 Corvettes in 2008 as an $1195 option. LS3 engines equipped with NPP get a bump in horsepower rating from 430 to 436. Modeled after the exhaust on the Z06, the exhaust uses a butterfly valve over one of the exhaust exit pipes (two total, one per muffler) to vary the exhaust output. It works similar to exhaust cut-outs popular on the street rods.


The exhaust control is operated by engine vacuum pressure. The system is tied to the pcm and monitors rpm and throttle position to measure "driver intent". Under normal circumstances the exhaust valve is closed and it routes the exhaust gas out of the other pipe after it passes through the baffle chamber of the exhaust. In this case it is quieter. If the driver accelerates hard the valves will open at 2,800 rpm as long as the driver is above 80% throttle. Between 30% and 80% throttle the exhaust will open during acceleration at 3,500 rpm.

The valves will be open for the first two seconds that the car is started. It requires time for the vacuum pressure to build to close the valves. After that The operation of the NPP is normally closed, open on demand. Have someone stand behind the car and bring up the RPM to 3,500 and you should see the valves open. The butterfly operation is tied to the throttle position sensor and the RPM. It uses the throttle position to determine driver intent.

Under normal operation the valves work as follows:

• Below 30% throttle and 3,500 rpm the valves are closed
• Above 30% throttle and 3,500 rpm the valves will open
• Between 30% throttle and 80% throttle and above 3,500 rpm the valves are open
• Above 80% throttle and above 2,800 rpm the valves are open

[1990 quasar blue]

Upon further investigation it seems that the difference is the npp has perforated tips and the z06 tips are solid. Btw these all seem to be getting more expensive by the day.

[-=Jeff=-]

Originally Posted by 1990 quasar blue

Upon further investigation it seems that the difference is the npp has perforated tips and the z06 tips are solid. Btw these all seem to be getting more expensive by the day.

Yeah cause everybody wants them. 3 years ago you could get a pair for $50
LOL

I have a solid idea to try, but it does not include the tips.. it is very close to the pictures posted earlier in the thread. if I bought the flappers the total I would have in it so far is $60

[Polo-1]

I think tips changed to all perforated after 2010?

The big thing is ZR1/Z06 are 3" and the GS and NPP are 2.5" pipe.

[1990 quasar blue]

I thought the difference in diameter was the inlet, not the tips?

[1990 quasar blue]

Originally Posted by -=Jeff=-

I have a solid idea to try, but it does not include the tips.. it is very close to the pictures posted earlier in the thread. if I bought the flappers the total I would have in it so far is $60

Do tell?

[Polo-1]

Originally Posted by 1990 quasar blue

I thought the difference in diameter was the inlet, not the tips?

You may be right... I just looked at mine, 3" in and 2 2.5 outlets one with valve ( that you want). I'm not a 100% on the outlet size for the GS/NPP's. I would ask around the C6 forums and see if someone would take a tape to it, and make sure.