2006-2012 Honda TRX90 TRX90EX/X Service Manual, Page 26Get this manual
GENERAL INFORMATION NOISE EMISSION CONTROL SYSTEM TAMPERING WITH THE NOISE CONTROL SYSTEM IS PROHIBITED: U.SFederal law prohibit, or Canadian provincial law may prohibit the following acts or the causing thereof: {1} The removal or rendering inoperative by any person, other than for purposes of maintenance, repair or replacement, of any device or element of design incorporated into any new vehicle for the purpose of noise control prior to its sale or delivery to the ultimate purchaser or while it is in use; or (2) the use of the vehicle after such device or element of design has been removed or rendered inoperative by any personAMONG THOSE ACTS PRESUMED TO CONSTITUTE TAMPERING ARE THE FOLLOWING ACTS: 1Removal of, or puncturing the muffler, baffles, header pipes or any other component which conducts exhaust gases2Removal of, or puncturing of any part of the intake system 3Lack of proper maintenance4Replaci ng any moving parts of the vehicle, or parts of the exhaust or intake system, with parts other then those specified by the manufacturer