how can i get to them?

 

If your talking about the bolts fron the header to the downpipe? You sould be able to get at them from under the car.. are you doing a header swap here or what ?

 

yea im lookin to put in a set of pacesetter headers after useing some extensions i got to the bolts downpipe to headers, but now the screws are rusted as a mother........

 

If your sure its imposseble, there not coming off, then your going to need to get them torched off ( acetylene torch) .. not much else you can really do .Chances are, if the bolts are rusted at the header dp connection then the bolts from the dp to the cat are going to be even worse.
I had the same problem, the bolts fromt the dp to the cat were not really bolts, it was just a rusted together piece so i took my car to the local rainbow muffler and they blew the bolts off for $6