The stock airbox pulls air from the right front wheelwell, iirc.
You might look for the Randall Cowl Intake - although this does require cutting thie firewall, it pulls ambient, high-pressure air from the base of the windshield. Hard to measure gains on a dyno (since it requires significant airflow over the car to be truly effective), but the theory is sound.
Combine it with a Track Dog Racing header blanket, and you'd probably have some noticeable gains, depending on how well calibrated your butt dyno is.
Personally, I'm not a big fan of true cold air intakes on street-driven cars, but that's because I've known more than one person who has hydrolocked an engine due to one (and poor decision making skills ).