  The amplitude of jet distortions and accompanying pressure and velocity
fluctuations resulting from Kelvin-Helmholtz instability of three dimensional
relativistic jets are explored. The effect of instability on jets as they
accelerate from sub- to super-Alfv\'enic speeds is explored and a relativistic
stabilization mechanism for trans-Alfv\'enic jets is proposed. The level to
which asymmetric instabilities on supermagnetosonic relativistic jets will grow
is predicted theoretically and a Doppler boosted ``apparent'' emissivity is
computed. Effects due to helically twisted filamentary structure produced by
asymmetric modes of instability should be readily observable on relativistic
jets.
