The only real suggestion I can make is to take the car to an independent shop (not the one that has done all the work on the car) and pay for them to go over everything.
I bought a dealer maintained car that had the trap oxidizer removed that had exhaust leaks from every connection due to loose bolts and nuts. Someone also broke off an allen wrench in a bolt that holds the oil supply line to the turbo, and kinked the oil line itself , and left if for me the unwary buyer to discover! Happily it is all fixed now after 10 hours in the garage(I'm slow). Don't
be afraid to get one of these cars because they are great, just try to do your checking before the fact. Good luck