Horn way too quiet

I have an extra pair of the bosch supertone horn FSA2, the big black one on the right of the link. I would want to add it on both my escalade and RRS. there is no space in the escalade but the RRS location is perfect. you can search youtube for sound.

here is my video on my pilot of the sound...

http://www.youtube.com/watch?v=d0NPbhFtvSI&feature=plcp



http://rb-aa.bosch.com/boaa-sg/Product.jsp?prod_id=83&ccat_id=35&language=en-GB&publication=1

Many folks here have installed Stebel Nautilus horns on our Rangies. Compact, simple install and super loud. Tone is in keeping with a euopean rig and definately gets peoples attention.