Just got my new TRC installed and it sounds like a bird chirping. Got on the phone with Yosh and they told me they are in the process of making a plug for the hole. They drilled a hole about a 1\2 inch from the exit of the pipe,and the pressure from the exhaust going threw the hole makes that noise. So I went and bought a stainless bolt to plug it, and of course it slipped and went down the pipe all the way to the header.Took it apart and got it out. got the bolt in and it sounds fine now. JUST A HEADS UP ON THE CHIRP CHIRP!!!!