DLC86
Fractal Fanatic
I think it's better to trim it before importing into the axe, cuz it trims it at the end too and you would end up with an overall shorter IR.+1, or negative mic values
Furthermore the ultrares processing applies a "window" to the IR which progressively reduces the high frequency toward the end of the IR, if you have some silence at the beginning this top end attenuation would start earlier (relative to the impulse) and you'd end up with a darker IR too.