Corsa and Lund are the only two exhausts I know made for the XLR though I have seen and heard a fabricated Borla. On a C5 I actually prefer the sound of a Borla but with the Northstar the fabricated Borla sounded a bit tinny compared to the Corsa and Lund. Lund was the deepest tone to my ear. As Harry stated, the Corsa will give the quad tips while the Lund gives you the tip from their Chip Foose custom. Corsa would be an easier do it yourself install.
K&N filters are available but no intake to date. :nodno