Those prices seem way out of hand to me. I have one of each and they sure arn't worth paying that much.
Cosmo I have the same horn and it's really loud on 12v and dosen't sound like a VW at all. Are you sure you don't have yours tightened down too much?
I'm not using the air filter do ya think I can sell it to some unsuspecting person for $150? Ha! I doubt it. $25 is more like it. Just my $0.02
George