Quick O2 sensor question

[gsodonis]

Can anyone please tell me if the 1992 SVX O2 sensor is a heated sensor?
My main catalytic converter is shot and I have already purchased a Walker replacement cat. I was going to have a muffler shop remove the precats and just weld in O2 bungs in the custom Y-pipe and reuse the stock sensors. The shop is warning me that if the precat O2 sensors are heated, the lack of the precat will result in lower temps at those sensors, causing the ECU to think the engine is colder than it is and running richer than needed.
- Does anyone know for sure if the sensors are heated or not?
- Has anyone removed the precats and noticed any problems with the car running rich?
- Should I replace the O2 sensors while I'm in there for the heck of it (my SVX has 93,000 miles) or should I leave the ones that are there alone (No steady CEL's at this time)

Thanks in advance for your help.