[rdorman]

I usually can make it go away with even gentle acceloration or deceloration. Also on the way home from Mid-Ohio I noticed that it often went away when I changed lanes.

Pretty sure it is linked to car speed. I will pay more attention next time. I already know about a exhaust gasket leak at the head, it sounds like lifter noise, which I what I first thought it was. But in listening to the valve train with my stethoscope I found it to be nice and quiet.

The echo is off of surrounding objects such as other cars, concrete barriers etc. With the echo I can hear it almost as much as the exhaust!

Rick