Get a deepwell socket that fits extremely tight. If I remember correctly, I think they're 14mm bolts, I may have hammered a 13mm socket onto them. I then just put a standard 3/8" socket on them and turned around so I could push it with my feet (remember, righty tighty lefty loosey). It was a pain, but they came off. I actually went by the local honda dealership and picked up some new nuts and then lost them so I just used hardware store nuts. The top bolt is a bitch but if you remove the muffler canaster first and then drop the B-pipe onto the ground and slide it over as much as the O2 sensor wire will allow, you'll get room to get to it. Don't stretch too far as you can overflex the doughnut gasket from the exhaust manifold to the cat.