Here are the instructions for getting at the connectors excerpted from my write up on upgrading to the Nameless Performance Cats. Hope it helps:

-- Set up very bright lighting pointing behind the throttle body.

-- From the right side of the car, locate the four oxygen sensor connectors. All four are behind the throttle body, in the main firewall harness area. All four are most accessible from the right side, but it is a very tight squeeze back there. There is a grey and a black four wire connector for each of the cats' two oxygen sensors. Three are in line right up near firewall, and one (the grey one from the driver side cat) is 90 degrees from the other three, within a bit easier reach from the driver side. They are extremely difficult to un-mate while on position on their mounting tabs. Instead, lift each connector pair straight up off its metal mounting tab. They will pop off with some direct upward force. Once off of the tabs. there is enough cable slack to squeeze the locking tab on each connector body and un-mate all four connectors.