TheClevelandSound wrote:ah....which produces more sound and which produces more HP
the exhaust or the CAI?
More sound would undoubtedly be the exhaust. It changes the sound of your car at all times... light throttle, WOT, idle, cruise, and coast will all sound quite different. the CAI only increases noise minimally at light throttle and moderately at WOT. it does NOT increase noise at idle, cruise, or coast.
More power depends on the system... but the CAI and exhaust are symbiotic systems. They will each give you more power, but COMBINED they will give you a sliver more than each individually. You will gradually get more power as you improve more related systems.
As far as getting the car to breathe better (which is what a CAI and exhaust do), you will get the best results from adding a CAI, an exhaust, headers, big bore throttle body (may not be possible with the DBW system?), and improved/reprogrammed ECU.
Basically, pick a system, upgrade it, then have a plan to save up for and move onto the next system.