If a car has the smog pump removed what purpose do the cats serve ?

 

none. and with no smog pump the cats are more likely to clog which can cause a bunch of problems

 

wrong, the thermactor air system is only functional on cold strat up/warm up phase in which the air the smog pump generates is diverted via the TAD VALVE into the exhaust stream to heat up the cats quicker/ bring them up to operating temp faster to reduce cold engine emissions quicker, once the engine is warmed up the cats are functional and remain as such, they will not plug up as a result of removing the smog pump, cats often mlug up due to excessive lean or rich conditions, those conditions as well as heavy misfires will plug up and or melt down the substrate

 

where i live the answer is still none. in ca we have to pass a visual test and without a smog pump the car fails so if its going to fail the visual, no reason to have cats

 

car will have less visual smoke and it will be quieter

 

The cats also smooth out the sound. Less/no cats, the more loud/raspy it will be. I'm curently running 2 cats without a smog pump, have been for around 3,500 miles and no problems yet. But my cars been running rich lately, so hopefully I dont run into the problems that Mjr46 said. But, I probably will, so thats why I'm going have them cut out I've been wanting my car louder and a little more raspier anyways.

 

I understand that, but I'm sure that's not what the OP wants to know and take into account where he lives in regards to his question. PA has a visual and emissions TO THE OP: not having a smog will have relatively 0 impact on the tailpipe emissions test if this is what your after???

 

I appreciate the replies I got on this. The only thing I was getting at was trying to understand what I was accomplishing by keeping the Kats on. The previous owner removed all the pollution stuff except the Kats.
He informed me when I purchased the car that he left the Kats on for the visual when he went to get it inspected. That still doesnt make any sense to me cause the pump was removed so maybe his mechanic never popped the hood and just looked underneath.
He was from the Philly area and probably had a little harder time getting it inspected than my mechanic is going to give me.
I was just trying to establish a reason to keep the Kats on. Minus the sound and supposed back pressure they supposedly give you.

 

Well......Didn't want to spend the extra $$ on getting the exhaust work done left that alone liked the sound?