Question about air horns- can I just use one (two came with it)- will this effect the loudness or motor?

hi ..... i recon as its not an exact science that one horn (u will have to block the other outlet from compressor) will be QUITE A BIT LOUDER than two and shouldent think its going to hurt the compressor.....alternatly fit an stebel nautalus compact air horn.......swat i did...