Changing Exhaust Note While Idling

[Roy W]

I've noticed since I put my 4" exhaust on that the exhaust note/sound at the exhaust tip changes while the engine is idling. With no regularity, the sound changes from a deep sound to almost quiet. I first noticed this when I drilled the exhaust manifold for the pyro with the engine running. I'm guessing that it's the variable vane turbo changing pitch while idling. Anyone else want to take a stab at it..???

[Kennedy]

That is just the turbo going through it's paces so that it can stretch it's legs and make sure that it doesn't stick. Common event.