I got this noise. Sounds like a exhaust leak on the hedders. I tightened all the bolts and felt around the hedders and the collector. I am almost positive it isnt that. Its not a rocker earthier. Checked for that. Im thinking it might be a lifter. I just put new heads on it. I doubt it would be a valve. Is there any sure fire way yo tell that its a lifter without taking off the intake?