High Flow cat with no O2 Sensor?

i just bought a magnaflow hi-flow cat online and went down to the mufflershop to have it put on and they said they couldnt do it because it didnt have a place to put the O2 sensor...ive searched and seen people talk about somethings that simulate the sensor and then some people mentioned drilling a hole and actually using the sensor.

i guess my question is what the difference would be between the two and how would i go about drilling a hole in the cat if i chose to go that route?

Jegs is one place that sells the 02 simulators,they probably have the sensor bungs.After getting the bung,just see hoe big a hole it needs and bore out the pipe and weld it in.
It would probably have been cheaper to just get the correct cat to start with--this high flow crap is just not necessary on a motor that sees less than 3000 rpm normally.
Wayne