I ordered an SMB high flow metal substrate cat and it does not come with an air pump inlet. How will it effect my car if i remove the airpump? My mods are in my sig.

Well you wont pass emissions but that is about all that will change. You might pick up one or two HP from the lack of parasitic strain the air pump makes. I doubt you will notice a difference though.

Will it change my idle?

it didnt change the idle in my car when i first took it off

I agree with Martin. It shouldn't change the idle at all.

Ok thanks guys!

You have a choice of removing "both" the air pump and ACV which includes the split air pipe and requires block off plates or you can just remove the split air pipe retaining the air pump which would work through the exhaust ports on the intake manifold. This is how I had my setup untill recently when I ditched it all.

I already got rid of that stuff when I went non-sequential.