  Within the transport BUU theory we study the influence of the choice for the
$\Delta$ resonance lifetime on pion-nucleus reactions and on heavy-ion
collisions at 1 A GeV. A quite small effect of these modifications on the pion
absorption on nuclei is found provided that the absorption probability of the
$\Delta$ resonance is modified consistently. Observable effects in the case of
heavy-ion collisions are demonstrated.
