If you get to see it in person, check the tread depth on all tires, look at the brake pads, open the hood and pop off the plastic cover and see if it’s got a new engine, check coolant level ...if you have time warm it up then turn off and check oil 15 minutes level. It’s not a Porsche so you don’t have a over rev DME counter. Check to see the exhaust valve works, see if it switches driving modes properly.
best few places: Odds and Ends Detailing
TLC Auto Detail
both a block away from each other OakGrove Road Herndon.
The 'best' Mustang mechanic is in the same compound - Jax Automotive
I had my GT done by Detail Authority
3131 Draper Drive Fairfax
oops I read that as PPF, not pre-purchase inspection. I would still recommend Jax Automotive and RRT racing - they do track inspections and alignments, or perhaps Three Pedals.