I had heard about this mass gathering of Mustangs a couple of years ago, but had just now stumbled upon some video on Youtube. Decent quality video at that. The occasion was on Sep. 30, 2007, at Rickenbacker Airport in Columbus OH - the Gathering of Mustangs.
There is nothing that sounds like a Merlin powered Mustang. Arguably the best fighter aircraft ever built (given it's time period), it is a magic machine. Easily the most prolific fighting warbird still in existence, it is a treat to see one or two at an airshow. For this meet, 20 (yes TWENTY) of them were in attendence. I truly wish I had been there to see this - a sight that hadn't been seen since the days of WWII - twenty P-51s in formation!