95db at 25 ft will be no problem unless you pipe it and turn about 16k rpm. I'm glad to hear you're open to joining a club. That first Cherokee would have paid for your club dues and possibly AMA fees too. The second one would have paid for your gas to go back and forth to the club field for probably a year.

To answer your question about the P51, if you feel like the Nexstar is fast, you'll find the P51 to be faster. The flying differences will include that the P51 won't roll away from the wind nearly as much or get tossed around on the ground by the wind as much, and that the plane won't right itself fast enough to save you from piloting errors. Rolls will be much smoother and more axial and inverted flight will be a little more stable.