Technically, cutting the stock antenna, actually shortens it receptability. Antennas are "tuned", to match frequency ranges. When you just go out and start cutting antennas, you could actually drop them fromt he receptability range they have, or at a minimum, drop the distance that it should receive signal at.
That's why with VHF and UHF antennas for repeater stations actually REQUIRE you cut the antenna, so that you can "tune" the antenna to the used frequencies.
Anyhow, just thought I'd throw that out there.