I have a question bout my 2000 s-10

[68C15]

removing the cat will totally screw up the way it runs. the EGR system needs backpressure, not enough and the engine will end up with a major bog under cruise and possibly burn a piston or 6. the SES (light) will be on therefor leaving the ECM in open loop so your fuel mileage will suffer and wash the rings ending up with an oil burner.
in short, do your mods after the cat and down stream O2 sensor.