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Discussion Starter #1
I just put a 2 chamber flowmaster on my 07 nbs silverado with turndowns just before the axle. The problem is when 4 of the cylinders shut down to save gas which is every damn ass 2 seconds it sounds annoying as hell. Is there anyway you can do away with that. If not I'm gonna have to go back with my stock muffler. It's sounds good one minute and like a big block harley with a exhaust leak the next.
 

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To hell with BHO!!
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I just put a 2 chamber flowmaster on my 07 nbs silverado with turndowns just before the axle. The problem is when 4 of the cylinders shut down to save gas which is every damn ass 2 seconds it sounds annoying as hell. Is there anyway you can do away with that. If not I'm gonna have to go back with my stock muffler. It's sounds good one minute and like a big block harley with a exhaust leak the next.
:LOL: I know what your saying man. My friends GXP is the same. Sounds normal one minute and like a WRX the next. Not a whole lot you can do other than changing exhaust.
 

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GM Trucks & UA
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I read (in Truckin' I think) that the new programmers comming out for the NNBS will let you program the gas saver out of there, maybe just stand by a while until those tunes make it on to the market...
 

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My '07 GMC Sierra NBS had the stock exhaust on when I test drove it. The 4 cylinder mode (whatever the heck its proper acronomious name is) was fairly undetectable. Before I took delivery, I had the dealer install a Corsa Sport Cat Back System on the truck. Sounds great under full throttle, and when it goes into that 4 cylinder gas saving mode, there's a slight and hardly noticeable muffled purr that I can hear. Nobody else in the truck hears it, but I do. However, it does not bother me at all.

I know the Dodge guys with the '06 and '07 Hemi Rams have a real issue with Dodge's 4 cylinder gizmo. It's real bad on those trucks. Some complain it sounds like a ricer takes possession of a truck with a non-stock exhaust.
 

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HOT AIR BALLOON OWNER
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Get a sound clip, I'd like to hear this. :rofl2:
 

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Discussion Starter #7
it wouldn't be as bad if it only done it when your driving down the road at a steady speed. But when I drive through town at 5 to 20mph it goes in and out almost like its going into overdrive(harleydrive) every few seconds, especially when your slowing down at a redlight. It's still annoying either way. Surely the new programmers can fix this!! if not I guess I'll just join the hells angels.
 

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I like the way mine sounds when the Active fuel management kicks in! Which is very rarely now that i have 37s and stock gears.:nono:
 

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resident pyromaniac
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I like the way mine sounds when the Active fuel management kicks in! Which is very rarely now that i have 37s and stock gears.:nono:
bwhaha. i was about to say, i dont recall hearing it on 4 cylinders at all when you were in myrtle:jester:
 

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bwhaha. i was about to say, i dont recall hearing it on 4 cylinders at all when you were in myrtle:jester:
The sound difference isnt like hearing a 4cyl and then 8cyl. Its more like a choppier sound when its on 4. By the way...i'll probably be coming up that way next weekend if yall MB boys are up for a little meet.
 

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Silverado Owner
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The feature is called AFM Active fuel management and it is NOT supposed to go into 4 cylinder mode under 20MPH
 

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I just put a 2 chamber flowmaster on my 07 nbs silverado with turndowns just before the axle. The problem is when 4 of the cylinders shut down to save gas which is every damn ass 2 seconds it sounds annoying as hell. Is there anyway you can do away with that. If not I'm gonna have to go back with my stock muffler. It's sounds good one minute and like a big block harley with a exhaust leak the next.

i have the same problem i put an imco 1 chamber on and choppped my exhaust to where it unbolts after the cats and it was loud as F*** but i got annoyed by that 8/4 cylinder thing...its not so bad now that iam lifted with bigger tires but when it was sock i hatted it....i heard that you can take your truck to your dealer and they can make the v4 mode less sensative and it wont kick in and out as much....but iam not for sure on that so dont quote me thats just what i heard...
 
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