I’ve been looking for a modification for my new-to-me car to help make it my own. I searched around the forums that deal with the Acura CSX and the Honda Civic and quickly realized that the simple “bolt-on” modifications available for the Honda Civic don’t work with the CSX as it has a slightly larger engine that was borrowed from the Acura RSX.
I started to home in on the engine’s air intake as a good place to focus my efforts. An air intake that allows more air to pass into the engine can increase the power (a little bit), this is done by decreasing the amount of effort to draw air into the engine and ensure there’s always enough. Less restricted air intakes also tend to improve the sound of the engine by allowing more induction noise to be heard.
Some Acura CSX owners had tried applying other Honda Civic-intended air intakes, but they would tend to trip the Check Engine light. The solution a lot of owners were coming to was modifying the airbox top cover to fit a generic cone-type air filter. The modifications involved trimming away most of the cover’s plastic and attaching a standard 3′ flange cone-type air filter to the now exposed tube. This not only involves a better filter but allows air to be drawn from more locations than the restrictive tube that leads to the front of the car – this could be the cause of the cars not-so-great throttle response.
Many Acura/CSX forums detail this DIY process, CSX DRIVER (login required – probably the best how-to), Acura Forum and this YouTube video of an obnoxious kid.