I only ask because on the other forums the guys there say they cut theirs in half.

The belmouth flares on both sides so they cut it in half to remove the flared side that would sit inside the airbox

http://www.triumphrat.net/twins-talk/25442-cheap-and-good-bellmouth-polaris-modification.html

06 Speedmaster, Chevy605 pipes, K&N filter, Polaris bellmouth, AI removed, Thruxton needles w. 2 shims, Kawi springs, 42/120 jets, Progressive fork springs, Progressive 412 HD shocks