Thanks for the info Mojave explorer,does your truck makes the same noise? i have owned a lot of cars and
trucks (nissan ) and i never heard any of them making this noise, anyway , i am taking the truck to the dealer to have them check couple of other issues i have with the xterra, while there i'm going to ask them to check this issue out.
Now for the mods you suggested Rockskier, are they expensive? and is this something you can do yourself? sorry i'm new in all this modification stuf