Headers/Cats/CAI shifting sound (whoosh?)

[mbowen89]

I just installed a CAI, Kooks long tube headers and high flow cats. Stock exhaust.

 

Whenever it shifts up, I get this whoosh sound. Can't really describe it, but it's exactly when it's shifting.

 

I'm also really surprised at how quiet this is even though it has LT headers and high flow cats, stock exhaust must really quiet it down! Except for this terrible sounding noise when shifting.

 

I drove it by my friends house and he said it sounded exhaust related... any idea what is going on?

[M1ck3y]

37 minutes ago, mbowen89 said:

I just installed a CAI, Kooks long tube headers and high flow cats. Stock exhaust.

 

Whenever it shifts up, I get this whoosh sound. Can't really describe it, but it's exactly when it's shifting.

 

I'm also really surprised at how quiet this is even though it has LT headers and high flow cats, stock exhaust must really quiet it down! Except for this terrible sounding noise when shifting.

 

I drove it by my friends house and he said it sounded exhaust related... any idea what is going on?

straight pipe it, you wont hear it anymore.

[mbowen89]

I was thinking of getting Borla TOURING catback.

I don't want it too loud, but I don't want to sound stock either.

 

Any idea what is causing this big whoosh noise during shifting?

 

[Denali_King]

I have the same setup on my 6.2 and I would describe it as raspy.  More rpm dependant.  I feel (I have watched the tach many times) if it shifts after 2500 and under 3500 it is definitely more noticeable.  Wot sounds fine. I don't know if it would be as noticeable with a 5.3 or not as it has a smaller exhaust system.  Turn up the tunes lol. I think the stock exhaust is obviously the cause.  My brothers 15 6.2 doesn't sound like that and his has a MBRP catback without headers.  

[RMR]

I have the Borla TOURING catback with the dual rear exit. Tame leaving the neighborhood and low rpm. Mild when you get on it. Inside the truck it has a rumble but right where I desire it. Headers will likely add to that a bit and make it more like the non touring.

[mbowen89]

1 hour ago, Denali_King said:

I have the same setup on my 6.2 and I would describe it as raspy.  More rpm dependant.  I feel (I have watched the tach many times) if it shifts after 2500 and under 3500 it is definitely more noticeable.  Wot sounds fine. I don't know if it would be as noticeable with a 5.3 or not as it has a smaller exhaust system.  Turn up the tunes lol. I think the stock exhaust is obviously the cause.  My brothers 15 6.2 doesn't sound like that and his has a MBRP catback without headers.  

So it's something you are really only noticing when shifting then as well? Why don't you go non stock exhaust to get rid of that?

 

Pretty sure I'm going to go Borla touring. See what it sounds like being tuned on a Dyno next month. Really hope that fixes it.

[Denali_King]

7 minutes ago, mbowen89 said:

So it's something you are really only noticing when shifting then as well? Why don't you go non stock exhaust to get rid of that?

 

Pretty sure I'm going to go Borla touring. See what it sounds like being tuned on a Dyno next month. Really hope that fixes it.

I don't want a cat back. It's nice and quiet running down the highway.  Headers are for more performance and the stock exhaust flows pretty well.   Didn't get to see mine dynoed (was on vacation and wasn't able to be there) or hear it for that matter.

[mbowen89]

Yeah but don't the raspy shifts bother you? Or did I misunderstand?

[Denali_King]

Not enough to go back to manifolds.  I thought about putting the 3rd cat back on but more work than it's worth and probably lose some power.

[M1ck3y]

The stock exhaust is extremely restrictive. I have corsa sport on my truck, which is basically a straight pipe. Corsa says with the 6.2 air flow increased by 404.40% over the factory exhaust. And I believe it, sounds like I have headers now. And If I actually installed my headers it would be insanely loud. I want the gm performance muffler (corsa touring) but you cant buy it outside of the kit.

[M1ck3y]

The swoosh sound is just exhaust flow. Related to whatever rpm your at when it shifts, and whether or not its killing power momentarily during the shift. Changes the flow of exhaust so you notice it by the swooshing. Its ticking you don't want to hear