[bkozlow]

My first question is are you attaching the headers only to the engine or are you not wanting to break that great seal you have on the mufflers to the header connection whether slip on or gasket seal. Try one side, disconnect the side pipes and do the headers only. Many times the weight of the whole system causes the installation of the header flange to be at a SLIGHT ANGLE TO THE HEAD, usually the bottom of the header flange is in slightly and this off set is enough to put less pressure on the upper
edge of the flange causing a leak on the top of the flange. Take the extra time to make sure the flange is square to the head. I like using a coupe of studs to hold the header up while I start the header bolts and when the bolts are in place remove the studs and replace them with a bolt. I found this reduced greatly leakage problems. The remflex gaskets are suppose to allow for 1/16 inch out of flat which is a great amount. A straight edge on the flange should give you some idea where the problem is.

Bill K