If you have an exhaust leak somewhere, you should be able to hear a burbling sound as engine rpms climb.  Locating the leak is easier done with two people, one to rev the engine, another to feel along the exhaust line for air coming out.  Similar to checking a bicycle tube for air leaks, run your hand along the exhaust about an inch away from the pipe.  (WARNING: Do not touch the exhaust it is hot and you can severly burn yourself.)

Here is how to fix a leak inbetween the front pipe and the catalytic converter...

Purchase a new gasket (from Daihatsu) and a can of plain silver spray paint.

This is a trick learned from Karl at Bill White Auto Mall.  Coat the new gasket in silver spray paint, let it dry almost all the way, and then replace the existing gasket.  As far as I know you can't buy official exhaust seal sealant, but silver spray paint seems to be metallic enough to do the job.  NOTE: This trick is not exclusive to Daihatsu Feroza, Daihatsu Rocky, or the Daihatsu Sportrak