Horn wiring diagram question about relay for air horn

I'm installing an air horn to replace the cheap excuse of a horn
that you can't even hear. Looking at the diagram (the red circle) shows
an existing relay for the horn.
Will this suffice for the air horn or should I install a separate
relay? I am thinking that installing another relay is redundant and
unnecessary. But this is based on what is shown in the service manual.
I could be wrong so wanted to check with others first.