Noise Laws-Air intake Mods, etc

[Tucson_02Silverado]

I'm posing this in Aftermarket since it is directly related to aftermarket parts.

 

I just noticed today in my 2002 Silverado owner's manual page 6-13...Federal Noise Law (EPA)...paraphrasing... over 10000 GVWR vehicle...even owners of vehicle may not alter the design of the airbox.  There is other mention of insulation, muffler's and clamps.  Rev limiter was also mentioned for no tampering.

 

Are there any SEMA members here that can obtain a clarification?

 

Is this why there are practically no listings for mods on 2002's or is CARB also painfully slow this year?