Plugging Holes in the Exhaust
 

I just bought a downpipe that has a hole for an Exhaust Temperature Sensor as well as one for the O2 sensor. I do not plan to use an EGT right now so I want to plug the hole. Any suggestions on how to do that?

bolt or go to an exhaust shop if it isnt threaded

But is there something like the teflon tape you use for plumbing, or, some kind of sealant that you put on the bolt before screwing it in?

You don't see anyone using sealant with O2 sensors, do you? It'll be fine with a plug and anti-seize compound.

it may need a brass or steel washer just like the o2 sensors.