Header Leak??

Those^^^ or a set of Remflex or Percy header gaskets are a good choice.

What headers do you have, cheapos or good ones. If you have decent headers the flange "should" be nice and flat, it's always good to check with a straight edge prior to installation though.

I use Stage 8 locking header bolts so they can't loosen up. I didn't want them backing out and blowing gaskets out.