hey guys, a friend of mine just bought a totally stock 2001 7.3, AT, 133k miles. it starts fine, seems to have good power for a stocker, but it has an intermittent "whooshing" or "shushing" sound. when idling cold or when driving it, we can hear a sound similar to if you were to put kitty litter in a steel pan and shake it back and forth. it seems to get a bit better/quieter when hot but will do it intermittently all the time but mostly just under load. any thoughts? have not pulled any codes yet - don't have a scan tool. the sounds does seem to be coming from near the turbo or exhaust. (I think I know what you're going to tell me but wanted to hear your ideas.) thanks.