Pretty easy to make a shield that attaches to your radiator and radiator ducting, which is free, as well as to your exhaust header, which is also free. The function it is performing isn't explictily illegal. That said, I'd never protest anyone that simply fabbed up a shield and attached it to the carbs. It is 2009 afterall and one needs to do what one needs to do to keep the dinosaurs running and more importantly running reliably.