07 2wd lanche with volant air intake, headers and exhaust. Nasty reverb sound when switches to 4cyl mode. Have driven many stockers and never heard nor could I tell when switching happened unless I was watching the dic. Im thinking it has to be the intake causing this and that it is a intake noise and not an exhaust. Any help appreciated.
Thanks,
David

 

I have a Gibson exhaust on my 07Avalanche. The 4cyl mode is very loud in it. I would guess that it is your exhaust, and it is normal

 

I first cut off my resonator, and I didnt hear it...then i added in a magnaflow muffler...and I too get this reverb noise. To me it sounds like its sucking the exhaust back in almost...But i would say its probably the exhaust creating the noise.

 

I hear same or similar thing and I have magnaflow cat back. When in V4, it is distinctive, but not really nasty sounding.

 

It's the exhaust...

 

I have the GM Perf. Exh. and in V4 mode, it sounds sort of like a muffled Jake brake on a big truck.

 

I think you guys have hit the nail on the head, thanks for all your replies. Now Ive got to decide if I can live with it. Ihad hoped it was the intake and if I chose to I could just remove it and go back to the stock intake but that doesn't seem to be the case.
Thanks again,
David