I have had mine on now for 2.5 years and 55,000 miles. I did not use the flange gaskets and haven't had a problem with the donut gaskets. I used sce copper gaskets on the flange with stage 8 locking header bolts. The only issue I have had is that one of plugs for the additional o2 bung fell out so i knocked the end off an old oxygen sensor and rammed it in there.