Leaking exhaust flange

What I did to mine was to heat and hammer the flange so the ears are slightly lower than the center and then filed the center area smooth and flat. When bolted down it gives it a little more pressure right around where you need it to seal. I also added a good stiff strap from the bellhousing/block bolts to the pipe. It helps keep the flexing to a minimum. I used one of those expanded steel looking flange gaskets.