lifter noise?

not a exhaust leak, I checked, and it is defiantly a collapsed lifter type tick, but like I said momentary, like it lost and collapsed than back to normal, kind of weird. and if exhaust leak would by all the time, this came and went... I also have the fancy dead soft aluminum header gaskets on it and no leaks anywhere, I took real close measures to avoid this. it sounds pretty damn good for a 318 with mp 340 cam , not too much,, dynomax ultra flows.. full headers 2.5 full piping...