Anyone use stock manifold gaskets with headers? I have a 2004 F150 with 49,000 miles owned since new. 5.4 3 valve with roush sc and true duals all into flowmaster super 44's. I installed a set of Boostbrothers 321 stainless headers which was a huge pain but one month later they are leaking, once the gaskets heat up you cant hear it, but it will probably get worse over time. Im afraid to tighten them anymore as the stock torque is only 20 lbs. any ideas?

 

Dont know if this is your case, but I have seen cases where the headers flange itself does not fit as flush as it should or may be slightly warped (or become warped) resulting in a poor seal. Also as it heats up the metal will expand some, which could increase the tolerances ultimately worsening the leak.

If you have not already, I suggest posting this in the intake and exhaust section.

 

These are high quality headers with a 3/8 solid flange and a thick laminated gasket.

 

Have you tried to re-tighten the bolts? There's good chance one or more backed off of had dirty threads when you tightened them and didn't hold. At some point, heat can burn through the gasket if exhaust gases are escaping through it.

 

Yes they are tight, couldnt get a torque wrench on them but ther tighter than the stock torque of twenty pounds. Im considering trying the stock metal gaskets.

 

FWIW, Dnyatech headers come with steel shim, factory type gaskets.