***Update***
Finally had my failing (rusty-rusty 2 horns) stock X5 horns replaced with 2 sets of Japaneese PIAAs at C$65 /USD 58 pee set on amazon. Each set has 2 tones/2 snails so now instead of 2, I have 4 horns trying to get to that buick/caddy type of presence. After having considered 330/400 Hz Superior Bass + 500/600 Hz Sport I chose the above Bass combined with the lower tone Sport version with 400/500 Hz. I sucrificed the 4th tone to keep more focus on bass. I like the way it sounds - lots of presence, but not too loud.

It could have been better with 4, but I made my choice in favour of lower 3 tones.

On a technical note, the locatuon of the horns on X5M is different from X5, i.e. not in wach corner of the bumper as that space is taken by extra radiators on each side. The horns are closer to center, but really deep behind the bumper. This means you can't go via wheel wells but have to remove the bumper just to replace the horns. I ended up paying for 3 hrs of labour for the bumper removal, rewiring for 4 horns vs 2 (no relay was needed btw) and for the fabrication of custom brackets.

Every service I see the confirmation of the words that "M" stands for money!!))

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2011 BMW X5M (was "loving the torque!" but used to it now - want more)
1997 Suzuki GSX-R750