Remove all the silence from Garageband exports, and I mean all

I am trying to make mp3s which I will then loop in a hardware loop player. However there are always about 2 seconds of extra silence at the end of the loop which obviously kills its usefulness as a loop. Other similar questions have been replied with "highlight the desired part of the track with Garageband's loop facility and export only that" - unfortunately I was already doing that, and it hasn't worked. Thanks for any help.