just finished replacing a header gasket. this will be the third time since i installed them. first ones lasted about a year, second ones two days, third leak right after i put them on. headers are doug thorleys. first gasket was the one that comes with the headers, the second two are mr gasket ultra seal i had laying around. this last time i used edelbrock gaskacinch sealer, supposed to work wonders. didnt this time. the gasket leaks out of the top of #'s 4+6. i think part of the problem is the way the y pipe tweaks the header, pulling the top out slightly. i'm hoping i can solve this by using a good thick gasket like what came with the headers, along with the gaska cinch. the mr gasket ones are pretty thin. what type of gaskets to you guys use?