Headers will always have that buzz to them but it can be reduced.. Add a resonator or change your muffler is really all you can do ;/

 

i had a similar issue....try a resonator before the muffler

 

yea... went to the shop... put on a HUGE resonator... very very long. this cut down on the sound quite a bit but it is still there... the buzzing sound doesnt bother me... its the loudness of the buzzing... its quite annoying. i love the headers, they are very classy under the hood and im quite proud to show them off... its just when im driving that i do get somewhat embarrassed... ppl dont like loud ass cars around here really.