did you have a cat on or in the header?

 

not on the 1.6... no cat

 

thats your problem then. cats do a lot more than you think soundwise

 

good to know!!

 

^ i have that exact same isue.. it started when we cut out the resignator due to an exhaust leak. it only happened in the higher RPM's then. then i had to get the whole intermidiate pipe replaced. and the one that came in was too long so they took out the cat, and now it does it in the popular mid rpms[:@] i am thinking on getting a full exhaust this summer maybe... but only if the wallet allows it, i just turn the music to drown out the buzzing