If it's the heat shield, just take it off! (You don't need it! Canadian Sportages had theirs removed at the dealer when they came loose) If the noise goes away problem solved, no money spent! If the noise does not go away you could spend money by taking it to a shop, or you could replace the cat yourself. Replacing the exhaust system may not solve the issue, as most (all) systems are sold as 'cat back' systems, and do not include the cat. You could remove the cat all together, but then you'd never pass 'air care' or what ever inspection you guys have down there.