Yeah... basically, I don't like anyone who thinks their car is the fastest shit on the road, and they have to prove it frequently.
Mustangs are pretty nice, and the new Mach 1s are a pleasure to drive. In fact, if I could have gotten a mustang GT comprable to my GS-R for the same price, it would have been a hard decision.
But about mustang owners that are asses: There are plenty of car owners that are asses. All you can do is acknowledge that children will be children, and be done with it.