i did compare the wall thickness, the new aftermarket DC headers do have a thinner metal wall. so i think the guy from the shop might be right. and the sound isnt like a metal scraping sound, its more of a buzzing. im also skeptical to put the old flex pipe on cuz for some strange reason i feel like the sound will still be there. and it would suck if i paid someone to cut the old flex pipe from my old headers, then cut the flex pipe on my new headers, and then weld it. that would cost some money and if the sound was still there, id be pretty pissed.

well i really appreciate your comments and your advice. i think im just gonna live with that sound. when i drive normal you cant really hear it. its not till i hit the gas pedal hard that it will make that sound. once again, thanks.