trying to put on a new catalytic converter and all the bolts on my manifold heat shield, etc. are really rusted even though thats to be expected. whats the best thing to use to get the bolts off, would it be best just to saw them off and just get new bolts? i dont feel like goin and trying to find the right bolt to replace them

 

Yes the rust is normal. Pick up a can of PB Blaster, douse them down real good and wait a good half hour before loosening them. If they don't want to come loose after that, then it's best to go ahead and replace them.