AWR PA Output Power Simulation - Credible?
Well, All simulations are wrong. Some of them are useful. 

You've got a behavioral model that claims a P1dB of 29.5 dBm, and a PSat of 33 dBm. The amplifier has 40 dB of gain, and you're putting in -0.5 dBm. Now, a perfectly linear PA would put our +39.5 dBm minus whatever the Low pass filter losses are. You're driving that amp pretty far into compression, so it really depends on how ADS has modeled compression. I'd suspect that the output directly out of the PA is +33 dBm, and that low pass filter is pretty lossy. Figure out what the low pass filter losses are, and you could figure it out

I suspect you're in the ballpark.