To help answer the OP's question, no. If you have a 3" barrel 9mm then the difference with +P over standard pressure will be negligible. There is a certain threshold in barrel lengths when 9mm gets to a certain velocity when a HP performs as it was designed. Paul Harrell on his YouTube channel has clearly demonstrated there is a huge difference in FPS between a 3", 3.5" and a 4.9" 9mm barrel using the same bullet. A difference of like 90fps more in a 3.5" barrel over a 3" barrel. That is a BIG difference.

he mentions that in the middle of this video