:help: my brother was driving next to me and he said my truck sounded like a motorcycle with a bad chaini . ( tight link) I have a stright pipe set up. I hear it too, sounds liek a playing card in ther spokes of a bike wheel... o3 lb7. 14000 mi please advise

You could be hearing the belt driven vacuum pump, do you have CA emissions?

no, it is from texas, no cat no nothing.. it seem really loud though.... only 14000 mi. scared the turbo fins are hitting the housing or something.. but i have no idea..