Possible header leak
 

I bought a Apexi GT header from a friend of mine. It seems fine no crack or anything. But after i installed i hear sort like BOV sound when i shift between gears at high RPM. I looked at it and found out that theres a small crack where the flange meets the B pipe part. I took it to the muffler shop and have them welded but the question is that i still hear a bit of BOV sound at high RPM. Can anyone tell me what is going on here?
Thanks.
Please email me back at hushpuppy@asia.com

Re: Possible header leak (MRSI00)
 

could be your intake if you have intake I have aem cai and when I turn off my car it sounds like it releases all this air.