If you're really worried about the turbo failing at 150k miles, then you should just self insure.
Example, lets say a turbo replacement will cost $5k, and you think you'll hit 150k miles in 10 years. That is 120 months, so put 42 dollars a month aside, and when you hit 150k, you'll have the cash on hand to replace the turbo. If you don't need the replacement, and you buy a new car, there is $5k you can use for a down payment.