47 CFR 95.337: Operation of impermissibly modified equipment prohibited.

No person shall modify any Personal Radio Service transmitter in a way that changes or affects the technical functioning of that transmitter such that operation of the modified transmitter results in a violation of the rules in this part. This includes any modification to provide for additional transmit frequencies, increased modulation level, a different form of modulation, or increased transmitter output power (either mean power or peak envelope power or both). Any such modification voids the certified status of the modified transmitter and renders it unauthorized for use in the Personal Radio Services. Also, no person shall operate any Personal Radio Service transmitter that has been so modified.