Not the fluffy house hold pet, but the one on my exhaust system. I heard that if you disconnect the smog pump it won't pump the needed air into the cat, and the cat will clog up. I will be removing the AIR system, but was going to leave the cat alone for a while befor putting in a cut out. Should I leave the smog pump hooked up untill I am ready to remove the cat?

 

An old wives' tale. The AIR adds more oxygen to the mix to make the cat more efficient (not the furry kind, the exhaust/emissions device kind). For cars designed for it, emissions will go up, which is mistaken for a clogged cat. If the cat clogged up, it was for a different reason (like too rich a mixture or a misfire).

Universal type replacement cats typically have the AIR tube on them. For applications that don't have the AIR routed to the cat, you just cap the tube (just did so on my van last week). For applications with AIR at the cat, you hook it up (will do soon w/Catco 3" on the Camaro).

Leave it hooked up. It doesn't hurt a thing. Removing it makes you a fugitive from (the EPA) justice (*****).

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82 Berlinetta, orig V-6 car, now w/86 LG4/TH700R. 2.93 limited slip. Cat-back from '91 GTA, Accel HEI SuperCoil. AMSOIL syn lubes bumper-to-bumper. Daily driver, work-in-progress (LG4 w/LB9 block, ZZ3 cam and intake, TBD heads ported & polished, Hooker headers & y-pipe, 3" Catco cat).
57 Bel Air, my 1st car. 0.030 over 396, Weiand Action+, Edelbrock 1901 Q-Jet, Jacobs Omnipack, 1-3/4" headers, TH400 w/TCI Sat Night Special conv & Trans-Scat shift kit, 3.08 8.2" 10-bolt w/Powertrax, AMSOIL syn lubes bumper-to-bumper. Best 15.1 @ 5800' Bandimere. Daily driver while Camaro was being put together.