What is causing this new noise

[eclipseman99]

Everytime I shift my exhaust make a weird gargel type noise.Its not a poping noise but it makes a baa bop bop kind of a noise.It just started doing this a few weeks ago.If I hold the throtle at 2000 rpms while in neutral is will make the noise also.

 

[racer]

hum I have poping sound and it doest it only under deseleration,at hihgher rpms wich is caused by badcompresion I think.