Have a exhaust(manifold)/header leak

[ultraflo]

You can get the Permatex orange hi-temp stuff at Advance Auto, Auto Zone, etc. and any speed shop would have it. Don't get carried away with that stuff (dont use too much) and let it setup for 15+ minutes before re-assembly.

You could also get a better gasket set if you are now running the junk paper ones. Lets see, they make em out of copper and I run the type Bassani sells with their headers (its a stainless plate with a graphite type removable gasket insert) and I think Earls or some other company makes something similar to it.

Both types work much better than paper...
Goodluck!