A header leak and an Intake leak are two different thing with two different problems. A header leak will cause an exhaust sounding leak. An intake leak would cause the vehicle to run like crap. It will miss, It will be sluggish, poor fuel economy. If it was a header leak it usually will not run bad, it will just sound loud. With that beings said, a header leak could cause you too suck in cold air and burn a valve. That too could cause the same issues as I have written above. With out knowing what the issues are, and not being able to hear what the vehicle is doing it would be really hard to diagnose the problem. I sure hope this helps. Good luck with it.