alright.. i have a 2002 dodge ram 1500 quad cab 4x4 with the 5.9L magnum 360. i bought the truck with a blown motor, had the motor taken out and bored out and fully rebuilt. had some aftermarket aluminum headers put on while it was out. just got it back from the mechanic and had safety and e-test done and it passed with flying colours. But... when im driving it and step on it sort of hard and make it rev up past around 2500rpm it starts to make a loud tff tff tff tff sort of sound.. sounds like air or something doesnt sound like metal hitting metal or anything weird like that an it still has power and accererates fine but the weird thing is you can only hear it when your driving the truck, if you sit in park or neutral and rev it you dont hear the sound.. pretty confused dont know too much about truck motors. more of a small engines guy. but i do know some.. anybody have any ideas?