I have seen people put the sensor before the turbo, in the exhaust housing and at the top of the down pipe. Im told that some people don't like putting the sensor before the turbo in case it breaks up and gives the turbo a bad day.

But as a temp measure, (temp measure lol... sorry) you can pick up hand held laser temperature measuring guns pretty cheaply, this would at least let you compare temps as you mess with timing.

Rob,