The cat is not hotter then your G/B, cat is under the G/B, then the G/B is under your center console, so removing the cat will do nothing much, upgrade the stock cooler n add cooler fan to it, should make a diff, some 8 owner try cook an egg on the center console B4. Malaysia weather so hot, my car also very hot on the footrest( downpipe + G/B ), Adding fan to the tranny cooler work reduced a lot of heat off my footrest n now is warm n can put my feet on it( thermal wrap + heat shield the downpipe should settle mine problem ).
Many mid G/B car also having this issue but RX8 G/B is so close the the body, that make it cooking hot, imagine 90-100C boiling water. Reduce temp on your G/B will prolong the lifespan of the tranny oil n G/B, only pro no con. Also can add heat shield or heat insulation under the console.
Many owner think its the cat but is the G/B...
http://i86.photobucket.com/albums/k95/effie5005/My%20Rx8/Image110Small.jpg