Mooney M20J Prebuy

[N9201A]

But unless there are high mountains that a J has to go around and the K can go direct, or unless there are strong favorable winds up in the flight levels, I'd wager the J is as fast A to B as the K.

And even where it isn't as fast, a J will usually have longer legs...on an apples-to-apples basis (stock tanks, equivalent vintage). So total trip time will often be less. I have found though that my willingness to fly those long legs has faded over the years.