Antenna frequency rating matter? (For home devices)
The answer is yes. If you had to replace the antenna there are specs you would have to match. Antennas act like frequency filters and have a range that they transmit (and receive). The impedance that the radio receiver and\or transmitter sees needs to be matched to the antenna.

One problem is you may make the situation worse, and it may be against the law. Because consumer devices are tested by the FCC for compliance, modifying the antenna may be breaking the compliance. Another problem is you aren't going to get any more power out of the transmitter.