2002 Lexus ES 300 catalytic converter

I am trying to remove the catalytic converter y pipe from the front and rear exhaust manifold cat pipes. On the rear bank I was able to loosen the 2 bolts holding the y pipe to the rear manifold with a 14mm socket as the nuts are welded to the flange. On the front bank the bolts are hidden behind a heat shield, but the nuts on the bottom do net appear to be welded to the flange. I tried the 14mm socket on these and the socket just jumps over the nuts, The bolt ends appear to have a torx type end on them which are not present on the rear bank. How do I remove the bolts on the front bank manifold connecting to the y pipe? Do I need to remove the heat shield and try to get a socket wrench on the bolts on top of the flange or do I need to do something with the torx type head on the end of the flange bolt?