I already have one probe installed in the exhaust manifold. When I install my TST do I have to drill and tap it again? I really want to keep the gauges I have. Can I tap off the same probe? How will it affect the TST if I don’t install the egt probe?

 

It shouldn't affect it at all except if u have the r49 it wont be able to read when to shut the fueling down so the egt's wont get to high.

 

Some have said that you can run two gauges off of the same pyro sensor. I would always be concerned that neither would be correct doing that, but that is just me.

I have two pyro sensors drilled and tapped into the exhaust manifold, one for the Autometer EGT and one for the TST. This works fine for me, this way I have validation that both are working/reading the same.