Convertible Exhaust Butterfly Valve - Service Bulletin

[fab410]

How would i fix the exhaust rattle noise??? I have an aftermarket exhaust and it still rattles at idle & low speeds

[sswiss3000]

Originally Posted by pannhead51

So was the sound louder/better ?

Well, As long as you have the AFM active it does make some odd noises when it kicks in. For me the engine seemed to exhale a bit less restricted, but not worth it as long as AFM is active.

[sswiss3000]

Originally Posted by fab410

How would i fix the exhaust rattle noise??? I have an aftermarket exhaust and it still rattles at idle & low speeds

The dealer will simply install two "O" rings around each spring. The source of the rattle noise is the spring it self. So their solution is to put two o rings around each spring which keeps it from bouncing back and forth when they are closed (not under tension).

[FUEGO]

I had the same problem thought it was an exhaust leak I had mine removed it sounds like its flowing 10 times better there is definitely a noticeable difference in sound a little more volume and aggressive tone I recommend this if you are considering

[SS PANTHER]

Originally Posted by FUEGO

I had the same problem thought it was an exhaust leak I had mine removed it sounds like its flowing 10 times better there is definitely a noticeable difference in sound a little more volume and aggressive tone I recommend this if you are considering

How did you have them removed? Did you have that small section cut out and reinstall and weld in a straight tube? I would like to get rid of them also. AFM has been tuned out and these make noise at idle and very low rpm. Annoying.

[thechileman]

We put a Magna flow axleback exhaust on our 2013 Vert. The valves were removed with the rest of the stock mufflers.

[steveintulsa]

I would recommend wiring or welding the valve open - really improves the overall sound (and an occasional poping at startup).

[teecee]

So with these removed or defeated is the drone inside the vert increased that much? Does anyone have any sound recordings before and after defeating them at idle, at cruising speeds both inside and outside their vert.

[sswiss3000]

Originally Posted by teecee

So with these removed or defeated is the drone inside the vert increased that much? Does anyone have any sound recordings before and after defeating them at idle, at cruising speeds both inside and outside their vert.

The sound is just a bit nicer (no Drone), but the coffee grinder noise from the AFM is much more annoying. So find the best way for you to get it deactivated

[teecee]

Originally Posted by sswiss3000

The sound is just a bit nicer (no Drone), but the coffee grinder noise from the AFM is much more annoying. So find the best way for you to get it deactivated

Good to know. Thanks.

[teecee]

Originally Posted by Convert-11

Used a pliers to move the spring to hold the valve always open rather than always closed- I believe I moved it 4 positions. Gives it a little more popping! Also eliminated the slapping sound from the valve springing closed when revving the engine.

So I wonder if moving the spring to a half closed position would reduce the popping introduced by full open, or even help reduce that coffee grinder noise under AFM for those that do not have a way to turn that function off? Just a thought.

I thought someone else posted in one of the related threads that they replaced the section of pipe with a short reduced diameter and it worked better than GM's intent with the flapper. Anyone recall that posting?