Mate, you didn't click on the link to Aussie Elises which I provided earlier eh?
The above SUS304 exhaust manifold + metal catalytic converter was designed specifically for the SC Exige and will bolt-up to your Arquay muffler. Don't worry about the Arquay catalytic, the Saclam exhaust manifold + metal catalytic converter is a more recent/well engineered product. In fact, the Saclam setup is second to none worldwide along with it's premium pricetag.