Is this true

[Bust]

Owners have reported an "aggressive" sound coming from the engine (by removing the top of the air box on 2000-up Neon). If you are thinking about any modifications, you should start here first.

Is this true? If so any input?

[Easy E]

Doesn't surprise me when you modify the air intake you can make the car sound louder. Don't expect much of a performance boost if any.

[bustamove]

No real noticeable performance gain with a CAI according to my butt-meter, but there are some benefits. Your engine will breathe better with the extra air flow and measurable gains are possible if you combine a CAI with an ECU upgrade and the right free-flow exhaust system.

I must emphasize that the right combination of mods is critical. Otherwise, the gains you seek may not be realized and the wrong combination may just result in money wasted.