Glad your turbine is running well on the bench and otherwise than the exhaust all is well. Mounting the temp probe is better when there is no metal to metal contact. I have seen people thread through the joint between the two strap halves but better to get a plastic strap around the thick end of the probe and affix it to one of bolts hold the mounting straps together. The probe is pushed as far forward as possible, this means you have too much length, however, you then make either a 'U' loop or circle which also assists the probe remaining fixed in position 2-3 mm into the exhaust and the main NGV gas exhaust flow.

Paul