[RED92LX50]

If you are sure the leak is at the header/h-pipe junction, you may be able to put a bead of muffler mender around the joint to stop the leak. It is smilar to using plumbers putty on leaky pipe joints. I used it on one of my connections and have not had any problems in over 6 years.

Otherwise, maybe the leak is at the heads - in which case you can retorque those bolts (as they can loosen a little after the inital install with the first few heat cycles).