Yep! Badly underpowered. It can maintain altitude and climb slowly, aerobatics are limited to rolls and stall turns.
It flew poorly in level flight, but in a dive I could feel it start to lock in and perform. I'm thinking of getting a 3530-1450 motor and using that instead, because this was just miserable at these speeds.
TBS, it flew respectably well for how slow it was, and had no bad stall tendencies. In fact, I couldn't make it stall at all!
I checked thrust on a motor calculator and it looks like I had a .4 to 1 thrust to weight ratio. Good for a glider, not so great for a p-51.