If you call dynamic dogfight a slow-speed one, then you're right.
But with the right tactics, you can do quite some damage with them.
I won't give away any tactics, but take your own conclusions: the P-47 is as heavy as a C-47, has one hell of an engine, can support very high speeds without disintegrating and is very well armed. For the P-51, the situation is a bit similar.
Quite easy to figure out what to do, eh?