is this a good buy?

found a 07 mustang gt, 28,000 miles, 1 owner older guy bought it new, mods are a vortec supercharger, its got the auto tranny that iam wanting, 4.10s, new torque converter, he says its got a mild tune, showed me dyno sheet, 368 rwhp, a couple time sheets 11.78 at 112 mph, it really drives out very nice. he is firm at 21,000. he bought a new 2011 5.0. thinking about selling my 86gt and buying this one, the 07gt is really nice.

i should have said the owner has been a dealer at a local ford dealership for over 15 years, he bought it new there, all the mods were done there, he had it dyno tuned at a local mustang shop down the street, iam a old fart dont know how to do the pics. stuff. but there is not 1 dent or scratch any where, interior like new, all leather int. iam trying to call him back to ask a few? about how much boost its tuned at and other stuff, never owned a supercharged car before. sure would like to buy it if no problems, sure runs out nice.