FWIW, and Im sure there will be disagreements to this, but Turbo Timers are pretty much worthless these days. Reason being is that the quality of oil has improved tremendously over the time period where all of the turbocharging tales of woe came to light.

I've been heavily involved in the turbocharged aftermarket pefromance market since the late 80s. In the last 10 years, I have never seen a turbo fail from oil coking. I've pulled turbochargers apart that had 200k miles on them and while there was wear, there was no evidence of coking.

Change your oil often, use a quality oil and save your money on the turbo timer.