For those horns, no.
That’s their preferred operating pressure otherwise you risk damaging the internals just like you would with blasting a K3 or K5 at 200 psi when it should be more like 120-150.
If you check out some of the videos from Big Mike Socal on Youtube (this one is a good example: https://www.youtube.com/watch?v=cjyUfV3W5zk) he plays with the pressure and you can hear the difference.
-Kris