So all 3 pulses out the driver's side pipe sound different than all 3 pulses out the passenger's side pipe?
I would expect an exhaust issue before a vacuum leak in that case.
Is the system new? If it is how sharp are the bends in the pipe that get it to the passenger's side?
If the pipe is small enough and the bends are sharp enough that might make the difference.
If the system is older and this situatuion is new then I would suspect an exhaust restriction.
Perhaps the muffler is collapsing internally?
Just out of curiosity how do you know for sure you have a vacuum leak?
