Tampering with the catalyser will make the bike illegal to ride on the road in most countries. Plus it’s bad for karma as the bike will be polluting more.
This said, you can find vendors selling straight pipes to replace the catalyser. But, be aware that the people at Coober ran the bike on a dyno with and without the catalyser and decided not to offer such a pipe due to the loss of power. They are working on a pipe that will replace the catalyser but still provide the necessary back pressure to avoid the power loss. (Coober confirmed their recommendation recently)
This loss of torque has been confirmed by another report by Kobi Liany on Facebook.